It was fun while it lasted for the Red Sox.

The 11-game run came to a sudden and unexpected halt on Tuesday. Once the Sox put the wood to the Indians to jump out to a 5-1 lead in the second and a 7-3 lead entering the bottom of the third, a 12th straight ‘W’ seemed inevitable.

The Sox, after all, had not lost any game all year in which they’d held the lead after three innings. Nor had Boston lost any game in which it had held a lead of four or more runs.

But Brad Penny and a surprisingly porous Red Sox defense allowed the Indians back in the game. By the end, it seemed fitting that the Sox absorbed a walk-off, 9-8 defeat against Cleveland courtesy of an error on one of the simplest plays imaginable.

With two outs and Mark DeRosa on second in the bottom of the ninth, reliever Javy Lopez got precisely the outcome he wanted: a groundball to the right side by Asdrubal Cabrera. Kevin Youkilis ranged to his right and made a diving stop of the ball before offering a perfect flip to Lopez covering at first.

But Lopez appeared to take his eye off the ball as he searched for the bag, and squeezed his glove too soon. The ball caromed off his glove, allowing DeRosa to score the winning run, and a shocked Sox club (several confounded members of the team lingered in the dugout and watched the Indians’ celebration) was dealt its first defeat in two weeks.

It only seemed fair that karma might offer a kick in the pants to the Sox by offering a reversal of the ridiculous teams that the club had claimed during its winning streak. They had erased 6-0 leads in two different games, and wiped out a 4-2 disadvantage when down to their last out against Mariano Rivera in another.

Now, with the run snapped, it is apparent that the Sox will not finish the season with a 156-6 record. Here are five other things we learned in the aftermath of Boston’s 9-8 loss:

1) DEFENSE MATTERS, ESPECIALLY TO BRAD PENNY

The Sox entered the game having allowed just four unearned runs on the year, tied for fourth fewest in the American League. They doubled that total on Tuesday, a fact that was largely responsible for their defeat.

After the Sox took a 5-1 lead in the second inning and a 7-3 advantage in the third, the game was theirs to lose. And lose it they did.

With no outs and runners on first and second in the second, Mike Lowell fielded a potential double play grounder but threw the ball away. Instead of getting out of the inning without a run (the next batter struck out), Brad Penny allowed two runs in the inning.

In the third, Penny again faced a first and second situation, this time with one out. He got DeRosa to bounce to Kevin Youkilis at first. Youkilis fired a perfect strike to Julio Lugo (appearing in his first game since July 11 of last year) at second, but Lugo squeezed his glove too early and booted the throw. An inning-ending play instead turned into a catalyst for a four-run inning that tied the game at 7-7.

There are some pitchers for whom an error or two will serve as little impediment. Curt Schilling, for instance, went a record 69 straight starts with the Sox from 2004-07 without allowing an unearned run, in part because he was a strikeout and flyball pitcher who was less reliant on his defense than some of his peers. As an example, in 2004 – a year when Schilling allowed two unearned runs – Derek Lowe allowed 28 unearned runs.

Penny, to this point, has been a defense-dependent pitcher with the Sox who seems ill-prepared to handle the responsibility of recording extra outs. He has struck out just six batters in his four starts, or roughly 3.1 per nine innings. That is the fourth lowest mark among major-league starters. (That said, Penny has not allowed as many as 10 unearned runs in any of his 10 major-league seasons.)

Speaking of Penny…

2) BRAD PENNY’S PERFORMANCE HAS BEEN MYSTERIOUS

It’s difficult to know what, exactly, to make of Brad Penny’s first four starts as a member of the Red Sox.

The good: Penny has a 2-0 record, has submitted a pair of quality starts in his four outings, and his velocity seems comfortably in the mid-90s, while the shape and variety of his secondary pitches (curveball, splitter, change) suggests useful raw material.

The bad: Everything else. Penny hasn’t been a strikeout pitcher in his career, but in his first tour of the American League, he’s taking it to extremes, and he’s been haunted by the fact. He’s given up five homers, and his streak of being taken deep in four straight starts matches the longest of his career.

Moreover, he threw barely half of his pitches (46 of 89, 51.6 percent) for strikes. He struggled to find the strike zone last night, and when there, did not command within it.

It would be one thing if he was traditionally a slow starter, but entering last night, April had been his best month (23-7, 3.52 ERA).

So, in some ways, the fact that Penny keeps emphasizing that he feels strong and healthy makes his early inconsistencies all the more puzzling.

Poor defense behind him aside, the outing against the Indians was his second batting-practice quality outing (following an eight-run yield two starts earlier, in which the Sox had to dig out of the 8-1 hole he left after three innings of work).

The Sox, of course, will not rush to judge a pitcher who showed immense promise this spring. Nonetheless, it has been lost on no one that a) Daisuke Matsuzaka is scheduled to throw off a bullpen mound on Wednesday and again this weekend before a rehab assignment lays the groundwork for his return; b) Justin Masterson is pitching extremely well as a starter; and c) there is enough talent in the bullpen that it can succeed without Masterson in it.

Speaking of the bullpen…

3) THE BULLPEN PECKING ORDER IS IN A STATE OF FLUX

The Red Sox acquired Takashi Saito to serve as the primary set-up man and alternate closer on days when Jonathan Papelbon was unavailable. Right now, he doesn’t look like the pitcher they had in mind for the job.

Saito, coming off an elbow injury, has shown velocity (92-93 mph fastball) that has been in line with what he featured during his dominant days as the Dodgers closer from 2006-2008. His results have been another matter entirely.

After the Sox reclaimed the lead, 8-7, in the top of the seventh, Saito entered to preserve it in the bottom of the inning. The fact that he was asked to pitch the seventh and not the eighth (Ramon Ramirez was set to pitch behind him) spoke volumes in its own right. But there was more.

Saito gave up a homer on a straight-as-an-arrow 93 mph fastball to DeRosa (who was seemingly involved in every Indians rally). He’s now given up two homers this year – or one more than he allowed in 45 games and 47 innings for the Dodgers last year.

The Indians tagged Saito for a homer and two singles on Tuesday. He’s now had two games in which he’s allowed at least three baserunners – the same number of times that happened in 63 appearances with the Dodgers in 2007.

Saito had to be bailed out by Ramirez, whose 12.1 scoreless innings this year leads the majors. The fact that Saito was in the game for the seventh, against the bottom of the Indians lineup, while Ramirez was being held in reserve for the top of the order suggests a) that bullpen roles are fluid and b) that in that fluid order, Ramirez has, in all likelihood, jumped ahead of Saito as the set-up man who will be asked to get the most critical outs.

4) IT’S A NEW YEAR FOR JULIO LUGO (AND, PERHAPS, THE BOTTOM OF THE ORDER)

Julio Lugo, who missed the entire second half last year with a torn quadriceps muscle and then was sidelined for the first 19 games of this year while rehabbing from right knee surgery, played in his first major-league game in more than nine months.

As mentioned above, he committed a costly error on a potential double-play ball, perhaps a byproduct of his timing still being a bit off.

“I don’t have my skills put together,” Lugo told reporters. “It’s going to take a while to get back into playing shape. It’s going to be a little bit before I’m playing at 100 percent.”

Offensively, he seemed more attuned to the speed of the game, helping to sustain rallies. In four trips to the plate, he collected a pair of hits (both singles) and a walk. His run-scoring single in the seventh – a nice piece of hitting, as he achieved solid contact with an inside-out swing that sent a hard grounder down the first-base line – gave the Sox a brief 8-7 lead.

Lugo had to be replaced by Nick Green at short for the bottom of the eighth, when his surgically repaired knee stiffened amidst the cold conditions of Cleveland. While his availability for Wednesday is in some question, the responsibility of turning over the lineup in stride is likely to fall chiefly to the 33-year-old.

The responsibility is not a small one. Part of the Sox’ early success has been the production of the last spot in the lineup, which had given the Sox an .820 OPS (fifth in the majors) entering last night.

In that vein, it was also noteworthy that Jason Varitek – batting eighth – turned on a 96 mph Kerry Wood fastball for a sharp single to right on a hit-and-run play in the ninth. That was the second pull hit by Varitek off of a 96 mph heater while swinging left-handed in recent days, the other coming on his grand slam against A.J. Burnett on Saturday.

Varitek is making contact with pitches that he could not catch a year ago. With nine strikeouts, he will likely have his fewest punchouts in a month since he had seven in April 2006.

5) THE STREAK WAS QUITE A THING TO BEHOLD

Though the 11-game winning streak is in the rearview mirror, it remains an impressive thing to contemplate. Indeed, it says a great-deal about the run that an eight-run eruption by the Sox on Tuesday (which included Dustin Pedroia’s fourth three-hit game in his last 11 contests, and two more hits and walks for Jason Bay) was barely noteworthy, representing a mere continuation of the team’s average scoring output during its march.

Obviously, a strong start guarantees the Sox nothing. In their last winning streak of this duration (a 12-gamer in 2006), they missed the playoffs for the only time in the past six years. Nonetheless, what the team did accomplish over the span of two weeks deserves recognition for its own sake.

Here are a few markers of a run that saw the Sox pull a hairpin turn from concern to confidence, going from one of the worst starts by the franchise in decades to its best April winning streak ever:

• The Sox outscored opponents by a landslide 83-37 margin, scoring the most runs in the American League during that stretch and allowing the fewest.
• The team hit 16 homers and led the majors in several offensive categories, including batting average (.314), OBP (.406), slugging (.558) and runs per game (7.55).
• Seven members of the Sox hit .300 or better. 
• The pitching staff forged the second-lowest ERA (3.00) in the majors during the streak. 
• Ten different pitchers had an ERA of 2.25 or lower. The staff allowed five homers during the run (11 fewer than their offense hit), fewest in the majors. 
• The Sox are the first team since the 2000 Braves to win at least 11 straight games in April. That Atlanta team finished the regular season with a 95-67 record before losing in the first round of the playoffs to the Cardinals.