BALTIMORE -- In a vacuum, it will hardly seem like a season-changing stretch. The Red Sox entered it two games under .500. They went 11-9 (a .550 winning percentage that would translate to 89 wins over a 162-game season) to pull themselves up to .500.

The team’s reward? The Red Sox are still in last place in the AL East, having trimmed just one-half game from their deficit in the division. The Sox were six full games behind the first-place Rays at the start of play on May 4; by the end of May 23, they found themselves 5½ games behind the first-place Orioles. And so, from afar, it would be easy to conclude that the Sox had done little beyond running in place.

Yet that assessment would fail to account for the full scope of what transpired. The Red Sox endured an obstacle course that seemed part test, part Job-like plague. They endured a 20-games/20-days gauntlet that included the placement of four players (three outfielders) on the disabled list. Their depth was not merely challenged but overwhelmed by the piling up of injuries, as the Sox now have 13 players on their disabled list.

Their roster now looks very, very different than it did at the start of the stretch of nearly three straight weeks of games. Yet while the roster tumult could have offered a rationale for the team to fail, the Sox resisted and held their ground.

“Like I said before the game, and I told the guys if they were listening after the game, just an amazing effort by a group of fabulous professionals who played through a lot of adversity, played through time zones, played through weather. [They] did one heck of a job winning these last two series,” said Sox manager Bobby Valentine after his team closed out the stretch with a 6-5 victory over the Orioles. “Going home at .500 is, I think, a feather in their cap. They played great.”

Naturally, there were plenty of elements to place under a microscope during a run that saw the Sox red-lining. With a run of 20 games in 20 days, it only seems fair to distill 20 lessons from a stretch in which the Sox played like contenders while moving within 1½ games of the second wild card spot.

And so, here are 20 lessons from the 20-in-20 stretch:

IT STARTED AT THE END, WHERE THERE IS NOW CLOSER COMFORT

In April, Alfredo Aceves offered the Red Sox little grounds for assurance at the end of games. He blew a pair of save opportunities in spectacular fashion, and while there were some interesting elements – foremost, a sudden boost in velocity to the mid- and high-90s – he finished April with more runs allowed (8) than innings pitched (7).

April seems like a long time ago for Aceves. Last September, it seemed almost impossible to imagine that a pitcher could do more for a team than Aceves did while logging 25 innings in the season’s final month and pitching in what felt like every game as the team’s most (and, at times, only) reliable reliever.

Yet a case can be made that he did even more during the past 20 days. He pitched a head-spinning 11 times (tied for fifth most in the majors), recording more than three outs in five of those games (including outings of 2 2/3 innings and 2 innings) while going 6-for-6 in save opportunities.

He had a 1.23 ERA while striking out 15 batters in 14 2/3 innings over the stretch. He produced more strikeouts than three starters (Daniel Bard, Clay Buchholz, Jon Lester) during the stretch.

“Aceves has a nice rhythm about himself, doesn’t he?” inquired Valentine.

That seems a significant understatement for a pitcher who was, more than anyone else on the team, a constant.

But…

ACEVES WASN’T ALONE

The bullpen as a whole was tireless. If one excludes the performance of Darnell McDonald, the outfielder conscripted into an inning of work in the 17th inning of a May 6 loss, the bullpen produced a 1.98 ERA while averaging 3 2/3 innings per contest.

A snapshot reveals several dominating performances:

Aceves: 11 games, 14 2/3 innings, 15 strikeouts, 4 walks, 1.23 ERA
Vicente Padilla: 10 games, 10 1/3 innings, 9 strikeouts, 3 walks, 3.48 ERA
Matt Albers: 7 games, 10 innings, 8 strikeouts, 5 walks, 2.70 ERA
Scott Atchison: 7 games, 9 2/3 innings, 5 strikeouts, 1 walk, 0.00 ERA
Andrew Miller: 9 games, 8 2/3 innings, 11 strikeouts, 2 walks, 2.08 ERA
Rich Hill: 10 games, 7 innings, 6 strikeouts, 3 walks, 1.29 ERA
Clayton Mortensen: 2 games, 6 1/3 innings, 6 strikeouts, 0 walks, 1.42 ERA
Franklin Morales: 7 games, 6 innings, 3 strikeouts, 3 walks, 4.50 ERA

Roles have become solidified. Aceves is the closer, capable of delivering more than three outs. Padilla is the primary setup man, one who is entrusted most frequently with stifling rallies when someone else has left runners on base. Hill and Miller (both of whom started the year on the DL; Miller, who was dominant against lefties throughout the stretch, wasn’t even on the roster until the third game of the 20/20 run) give Valentine flexibility to match up in the middle innings. Atchison and Albers can offer multiple innings in the middle of the game.

Most had a rough game or two at some point, but by and large, the collective effort of the relievers was extraordinary, particularly given how unsettled the late innings seemed before the run.

“We have three guys at the end of the game now who came to spring training as starters. We didn’t pitch them an inning in spring training in this type of role,” noted Valentine. “The bullpen has done a fabulous job of answering the bell. I think they’ve gotten stronger collectively because of the adversity that was faced.

“Sometimes, when I was talking about the team, sometimes that’s the reason not to be good. excuses, some people do it. They weren’t going to allow it to be that. I think, you know, we’ve just been, I don’t want to say lucky, but it’s been, we’ve had those days, when they were needed, we got them.”

And that’s a reflection not just of the bullpen members, but also the fact that…

THE MANAGER SEEMS TO HAVE AN EVER-IMPROVING FEEL FOR HIS PITCHING STAFF

This is what happens when teams pitch well. The manager looks very good.

There were times in April and even early in the stretch of 20 games in 20 days when Valentine seemed like he was struggling with the timing of his pitching changes. A couple times a week, it seemed as if he was leaving a starter in a batter or three too long, and the relievers were entering games under impossible circumstances.

No longer. Valentine has had a bit of a quicker hook, and he’s repeatedly pushed the right buttons, whether with his relievers or with a move like Wednesday’s defensive substitution, when he put Che-Hsuan Lin in right field just in time for the outfielder to make a spectacular diving catch that saved the game.

Valentine said before Wednesday’s game that bullpen management and navigating the late innings remains a work in progress. But the emphasis is on progress. And with the decisions clicking, virtually everyone on the pitching staff looks better, particularly at…

A SOLIDIFIED TOP OF THE STARTING ROTATION

In 20 starts, Sox starters averaged 5 2/3 innings while going 10-7 with a 4.61 ERA. As a group, they had 5.7 strikeouts and 4.1 walks per nine innings, all of which suggest an unsustainable formula for success.

Still, individually, there was promise, particularly from the three starters who have established themselves as the most reliable contributors for the Sox to date.

Jon Lester appears like he’s begun his familiar May takeoff, as he had a 3.12 ERA in four starts. He had surprisingly few strikeouts (4.8 per nine innings) but walked just 1.7 per nine frames, and he showed the makings of the pitch mix he needs to be a top-of-the-rotation starter.

Josh Beckett laid an egg coming off his controversial lat injury/golf outing/10-day hiatus, but he followed that with dominant outings in both Seattle and Philadelphia.

Felix Doubront might not be working past the sixth inning, but the Sox really don’t care that much, given that he’s been overpowering for six innings at a time. In 24 innings, he led the rotation with a 2.62 ERA and 23 strikeouts while allowing just one homer.

Beckett’s controversial stinker notwithstanding, all are showing the ability to mix pitches and to deliver consistently competitive -- and sometimes dominant -- outings. Lester has been reliable. Beckett has seemed, for most of his starts, capable of shutting down his opponents. Doubront has been a revelation, getting swings and misses at an elite rate.

Entering the year, the Red Sox hoped to have at least three starters operating at a very high level. They’ve gotten it, just not necessarily from the expected sources.

And that is because…

THE MYSTERY CONTINUES WITH CLAY BUCHHOLZ AND DANIEL BARD

While Daniel Bard has been something of a mystery given the fact that his strikeout and walk numbers have been turned on their head (in four starts, he had 17 walks and eight punchouts, numbers that seemed more likely to be reversed), he’s kept the Sox in every game he’s started while delivering no fewer than five innings. He seems optimistic that there is something to build on.

“I don’t feel like myself out there pitching right now,” he acknowledged after earning a win on Wednesday. “I know that, when I get right and I get my mechanics where I’m supposed to be and I’m getting ahead of guys and trusting those pitches with two strikes, the strikeouts are going to come.

“It’s a little frustrating, to not get it when you need it,” he added. 
“[But] the mechanics, we’ll work that stuff out between starts. To be able to get the win today is huge.”

Even Clay Buchholz showed some improvement, submitting his best two outings of the year even as he forged a 6.64 ERA in four starts.

All of that said, a run of nine quality starts in 20 games is not a sustainable formula for success, and Bard and Buchholz must both be better in order to improve on such a figure. The need for them to do so is particularly acute given…

THERE IS A STARTING DEPTH PROBLEM

The Red Sox had Aaron Cook waiting in the wings as a rotation reinforcement in case anyone faltered. He concluded a terrific run in Triple-A in April, got called up at the start of May, and promptly suffered a significant flesh wound in his first and only start to date for the Sox on May 5. The laceration still hasn’t healed, and he remains unable to start a rehab assignment.

Meanwhile, Daisuke Matsuzaka struggled both on the mound and physically, resulting in a cortisone shot to his right trapezius muscle and a reset of his 30-day rehab clock.

Those two right-handers represented the Sox’ foremost depth options to open the year. In Triple-A, the Red Sox feature veterans like Ross Ohlendorf and Justin Germano, serviceable right-handers with big league experience, but lack apparent impact arms.

That, in turn, has given the team little choice but to ride out some of the inconsistencies of Buchholz and Bard. It would be one thing if they had a top prospect -- someone like Buchholz in 2009 -- waiting in the wings. They do not, and with Cook and Matsuzaka unready to help, the Sox need to hope their current starting five holds its own.

But whereas the Sox showed an absence of rotation depth…

THE LINEUP PROVED CAPABLE OF WITHSTANDING A RASH OF INJURIES

No Jacoby Ellsbury or Carl Crawford or Cody Ross or Ryan Sweeney or Darnell McDonald or Kevin Youkilis? Pfff.The Sox remained one of the top offenses in the majors despite having a wrecking ball run through their roster. They scored 5.2 runs per game, second most in the American League to the Rangers over the past 20 days.

They required both unexpected and creative solutions in order to endure the stretch. They got them, and may continue to do so, since…

THIS ADRIAN GONZALEZ-IN-RIGHT FIELD THING COULD WORK

It’s not a perfect solution. By his account, the best-case scenario for Adrian Gonzalez is that he is an average major league right fielder. Valentine and GM Ben Cherington both insist that it’s not a long-term solution.

Yet at a time when the Red Sox have been so badly depleted that both of their primary center fielders (Marlon Byrd, Scott Podsednik) were acquired after the season started, an average/adequate right fielder who gives the Sox a significant lineup presence is a significant development.

Gonzalez demonstrated that his baseball instincts and field awareness -- not to mention some prior outfield experience in right thanks to a winter league season at the position in 2005 -- can permit him to handle the position credibly. His ability to chase down a foul fly ball against the right field fence at Camden Yards on Wednesday stood out.

There is some understandable hesitancy about entrusting Gonzalez -- a player for whom foot speed is an oxymoron -- with right field at Fenway Park. However, it is worth noting that the 2007 World Series team featured more than a few games in which Eric Hinske -- himself no burner -- patrolled right field in Fenway. The Sox survived.

Now, at a time when using Gonzalez in right permits the Sox an opportunity to have both Kevin Youkilis and Will Middlebrooks in their lineup, the idea of Gonzalez patrolling a massive outfield expanse does not seem ridiculous. There may come a time at which Gonzalez’s lack of range is exposed, but until then, the payoff from the experiment is fairly obvious.

That said…

ADRIAN GONZALEZ IS STILL SEARCHING AT THE PLATE

Gonzalez has had his moments. He reached base in all five plate appearances agains the Indians on May 11, crushed a homer to right in Philadelphia on May 18 and led the Sox with 10 doubles while tying Will Middlebrooks for the team lead in extra-base hits with 11 during the stretch.

But the games in which he’s had a significant offensive impact – the kind that were customary in 2011 and in the five previous seasons in San Diego – have been isolated rather than clustered. He has not gone on the kind of sustained role on which the Sox rely.

During the roadtrip, he hit .289 with a .341 OBP, .446 slugging mark and .787 OPS. By his standards, those numbers suggest a slump, as does the fact that he struck out 20 times in 91 plate appearances.

WITH GONZALEZ SLUMPING, KEVIN YOUKILIS’ RETURN IS EVEN MORE SIGNIFICANT

In his first two games back from the disabled list, Kevin Youkilis offered a reminder of his tremendous offensive skill. On Tuesday, he blasted a mammoth homer to center against an otherwise unhittable pitcher in Brian Matusz. On Wednesday, he followed that up with even more impressive at-bats, going 2-for-3 with a pair of two-strike singles while also drawing a walk.

His two-day line: 3-for-6, walk, HR, 2R, RBI, BB, 2K.

The Red Sox need middle-of-the-order bats, particularly with Cody Ross down. Offensively, Ross had one of the best runs during the 20/20 stretch, hitting .275/.387/.569/.956 with three homers in 14 games before a fractured foot placed him on the DL. In that sense, the return of Youkilis could not have been more well-timed, nor could the willingness of Gonzalez to spend time in right to accommodate a lineup that features both Youkilis and Will Middlebrooks.

Speaking of…

WILL MIDDLEBROOKS PASSED HIS FIRST MAJOR BIG LEAGUE TEST

Call-ups get to the big leagues and make an instant impact all the time. Middlebrooks did so in somewhat exaggerated, historic fashion (becoming the second player since 1900 to have extra-base hits in each of his first five big league games), but certainly he wasn’t the first player to look like a Hall of Famer in his first handful of games.

And then reality sets in. Such seemed to be the case for Middlebrooks, against whom pitchers started making their adjustment while holding him to a 6-for-36 stretch in which the rookie struck out 15 times.

But Middlebrooks did not relent to the slump. Instead, he regained his footing, going 9-for-23 with a line of .391/.391/.609/1.000 over his last six games. The fact that he’s totaled three walks against 26 strikeouts in his first tour of big league duty is a reminder that further refinement of his plate approach, borne of experience, is needed. Nonetheless, his .551 slugging percentage while playing in 19 of 20 games underscored the fact that the precocious third baseman is capable of making an impact even while he learns lessons on the fly.

Middlebrooks is not the only Sox hitter who is getting on base at a low rate while producing big slugging numbers. But another member of the club with a similar offensive formula is residing in a very different part of the order, a reminder that…

THE RED SOX HAVE A HITTER WHO LEADS OFF, NOT A LEADOFF HITTER

The absence of Jacoby Ellsbury has been felt most profoundly in two areas. First, his Gold Glove-caliber defense is not easily replaced (though Che-Hsuan Lin could say a thing or two about defensive excellence). Secondly, no one else on the roster seems comfortable hitting leadoff.

Mike Aviles has become the go-to option for that role. During the 20-in-20 run, Aviles showed the same aggressive approach that defines him as a guy with a low on-base percentage but the ability to drive the ball.

He hit .259/.273/.447/.720 during the stretch. It is worth noting that, on the season, Aviles is hitting .357/.400/.643/1.043 as the first batter of the game, and he's played defense at such a tremendous level that the combination of his glove and his slugging meant that the Sox didn't even consider calling up Jose Iglesias so that they could send Aviles to the outfield when Ross and Sweeney were injured. Still, the Sox are giving the most plate appearances to the regular who has the worst on-base percentage on the team. It’s an imperfect fit, but to date, the Sox haven’t felt comfortable with another candidate.

They’ve needed contributions from elsewhere in the order to offset the fact that Ellsbury isn’t at the top of the lineup. They’ve gotten them, perhaps most spectacularly from behind the plate.

On that subject, it is worth noting…

THE RED SOX CATCHING TANDEM HAS BEEN A BEAST

At times in April, the combination of Jarrod Saltalamacchia and Kelly Shoppach seemed like it could not deliver what the Sox needed from the position. The view of that duo’s contributions is very different now.

Over the past 20 games, Saltalamacchia and Shoppach each hit .308 and among players who were in more than two games, they were tied for the team lead in slugging with a .615 mark. They combined for five homers and 13 extra-base hits over the 20 games.

The result? The Sox have gotten more production from their catchers than any team in the American League. After Shoppach went 2-for-3 with a two-run homer and a walk on Wednesday, Sox catchers lead the AL in homers (9) and OPS (.899). Saltalamacchia and Shoppach have a combined line of .283/.339/.560/.899 this year, making the production from that position one of the foremost areas of team strength through this stage of the year.

Those contributions have been unexpected, but not nearly as unexpected as…

THE SECOND CHAPTER OF THE DANIEL NAVA STORY

Daniel Nava wasn’t even deemed worthy of an invitation to big league camp. His meteoric rise to prominence in 2010, when he hit the first pitch of his big league career into the Red Sox bullpen for a grand slam, seemed like it might be the proverbial flash in the pan.

Nava was removed from the 40-man roster in May 2011, at a time when he says he couldn’t hit water if he fell out of a boat. But he did not give up, and instead decided to repeat his tale of remarkable perseverance.

He would not have been in position for a callup this year but for the extraordinary run of injuries and his own excellent performance in Triple-A. But when the improbable and unexpected happened, Nava was ready.

He’s played in all 14 games since his callup, and he has been the team’s best hitter over a two-week stretch. He is hitting .350 with a .491 OBP (!), .600 slugging mark and 1.091 OPS.

Obviously, it is not a sustainable stretch. But regardless of what happens going forward, Nava played a crucial role in helping the team to get some stability from its outfield play.

But his was not the only unexpected contribution during the stretch. After all, one player who contributed to the Sox’ latest victory wasn’t even in the organization at the start of the run.

SCOTT PODSEDNIK. REALLY?

Like Nava, Scott Podsednik had not played in the big leagues since 2010. And there wasn’t a clear reason to expect that he would be back at that level anytime soon.

At 36 -- an age when a player whose primary attribute in his lengthy big league career was speed -- Podsednik was hitting .203/.289/.216/.505 for Philadelphia’s Triple-A affiliate, and by his own admission, he’d become “stale” there. An outsider might have looked at such numbers and concluded that the outfielder was done.

Yet just a week and a half after acquiring him for cash, the Red Sox needed to add him to the big league roster to provide a steadying veteran to step in amidst an injury epidemic, and Podsednik -- who found his stroke in Pawtucket, where he hit .323/.371/.484/.855 with a homer in nine games -- played a significant role in a pair of rallies on Wednesday, singling in front of Kelly Shoppach’s two-run homer and later delivering a homer of his own, the insurance run that offered the ultimate margin of victory.

Go figure.

Podsednik’s contributions ended up representing the difference between victory and defeat. And that, in turn, served as a reminder that…

IT TAKES A TEAM

A couple of isolated performances would not have been enough to carry the Sox through the stretch of games they endured. In that respect, the team’s final game of the stretch -- in which the seventh (Nava), eighth (Podsednik) and ninth (Shoppach) hitters all went deep, the first time that the bottom third of the Sox lineup had gone deep since Aug. 3, 2003 -- served as a fitting emblem of what will be needed going forward.

David Ortiz, it turns out, is not going to hit .400 for a full season. He struggled at the end of the 20/20 stretch, and finished with a .224 average, .314 OBP, .434 slugging mark and .748 OPS over those games. Nava, it seems safe to assert, will not finish the year as a triple crown candidate.

But if the Sox can get different players contributing at different times, then they will find a high level of play to be sustainable. And the Sox will need to keep pulling rabbits out of an outfield hat, because…

IT’S GOING TO BE A WHILE BEFORE THE REGULARS ARE BACK

Best-case scenario for Jacoby Ellsbury and Carl Crawford in the eyes of the team? Sometime in July, perhaps, they will be ready to return from their respective injuries. GM Ben Cherington suggested that Ross could be on a similar schedule, as the fracture of the navicular bone in his left foot typically requires six to eight weeks to heal.

And so, the test of the team’s outfield depth is not even remotely over. Players like Nava and Podsednik and Gonzalez and Marlon Byrd and Che-Hsuan Lin will continue to patrol the outfield for some time. Darnell McDonald (oblique) will be back soon and perhaps Ryan Sweeney (concussion) will also be capable of getting back on the field in the near future, but the depth test will continue for some time.

So far, the Sox have received top marks in that aspect. If they can continue to do so, it will verge on miraculous.

THEY CAN LIVE THROUGH CONTROVERSY

In retrospect, Josh Beckett’s Golf Gate bordered on laughable. There was a perception issue in play, of course, but there was no real physical risk involved, given that he had experienced some brief soreness -- and no more -- after his 126-pitch outing against the White Sox at the end of April.

The Sox had an extra starter available (Cook) whom they needed to add to the big league roster. They decided to scratch Beckett as a precaution. And then all hell broke loose because he went golfing on the off day immediately preceding the stretch of 20-for-20.

The pandemonium was stoked by Beckett’s own refusal to show any remorse or compassion for those who questioned his decision. But while it was a relevant topic for about a week -- more or less until Beckett dominated the Mariners -- the Sox were able to move on from it.

And that is in part because…

YES, THEY CARE, AND YES, THERE IS LEADERSHIP

It is not possible to say whether the team meeting called by David Ortiz served as the catalyst for one of the best sustained stretches of play of the season by the Red Sox. But the Sox are now 10-3 since it took place, the best record in the AL over that span.

The fact that a meeting was called, and that the team reacted by playing some of its best baseball of the season, offered a suggestion that there is leadership and underscored the fact that the team does care. Such ideas should be obvious, and in other seasons, would have been taken as a given.

But coming off the collapse of September 2011, skepticism about the club’s attitude was completely understandable. This stretch of games has been the first time in which the team has been able to separate itself from the baggage of the end of last season, in which the clubhouse could insulate itself from the noise on the outside.

At the end of last season, that was not the case. Indeed, the exact opposite proved the case at the end of last year, when meetings called by both former manager Terry Francona and Ortiz had something between no impact and a negative impact.

And so, for the first time, there is evidence that things are different this year. An perhaps that helps to explain why…

THEY ARE STILL THINKING BIG

In relative terms, it was just a blink of an eye. Over the course of a 162-game season, 20 games represents just 12 percent of the season. It’s nothing.

But given the unusual circumstances that confronted the club, it was a stretch of immense significance. The team’s finishing kick, in which it won four series (against the Indians, Mariners, Phillies and Orioles) while splitting another (against the Rays) offered the team something that had been lacking before: Results that could give the team conviction about what its roster is capable of achieving.

"We play like this the rest of the season," Valentine said on NESN after Wednesday’s win, "we're going to win the championship."

On its face, the statement seems a bit ambitious. The Sox are now a .500 team. All four of their divisional rivals are ahead of them. That being the case, the boast ultimately may prove idle, but the fact that the Sox can talk in such terms without sounding as if their heads are in the sand suggests that the team has reached a new stage in the 2012 season.