Facing elimination in a playoff series? That’s a must-win situation. A three-game losing streak in April? Clearly, the same dire consequences are not in play.

Certainly, the Red Sox had not moved to DEFCON 1 on the basis of three defeats – two to the Tampa Bay Rays at home and another in the series opener against the Angels on Friday – in the season’s first week. Even so, it would be tough to say that there wasn’t some hint of elevated stakes in the fifth game of the young campaign.

It’s well and good to say that April contests don’t have the same heft as other contests later in the year. But then, if yesterday’s game wasn’t that important, then it seems unlikely that Jonathan Papelbon would have been brought in with two outs in the eighth inning for a four-out save.

Manager Terry Francona told reporters that his team’s 5-4 win over the Angels in Anaheim “felt like a playoff game.” That statement reflects not only the caliber of the opponent (a team that the Sox have faced in the ALDS three times in the last five years), but also the fact that a victory allows the Sox to breathe a bit more easily.

Here are five lessons from the first come-from-behind Red Sox victory of the 2009 season:

1) BRAD PENNY GAVE THE SOX EVERYTHING THEY COULD HAVE HOPED FOR

Brad Penny made just three spring training starts against major-league hitters. The Sox had hoped to continue building his pitch count by sending him down to Fort Myers to throw roughly 80 pitches in a minor-league camp game on Tuesday. Instead, the team had to limit him to a bullpen session of roughly half that pitch total when his first start of the year was moved up by a day due to the Opening Day rainout.

In his first regular-season start as a Red Sox, Penny was limited to roughly 85 pitches. It wouldn’t have been surprising to see him reach that total without getting through five innings.

Instead, Penny logged six solid if unspectacular innings, allowing three runs on five hits and two walks. A short outing could have crushed the bullpen for both Saturday and Sunday. Instead, Penny got deep enough to put his team in position to win, and to set himself up for his first win in Boston.

Penny criticized himself after the game for setting up all three runs: walking Chone Figgins and allowing him to come around to score in the first, and permitting solo homers to Mike Napoli in the third and fifth innings.

Penny was not dominant. He got just two swings and misses (both at fastballs) over the course of the afternoon, suggesting that he was neither overpowering nor deceptive.

Still, his fastball velocity increased as the game progressed. His 86th and final pitch of the afternoon a 95 mph fastball that resulted in a Kendry Morales swing and miss for a strikeout.

Penny was ecstatic about how strong he felt over the course of the outing. If true, then Saturday’s win could be a solid point of departure in what the pitcher hopes will be a major rebound season.

2) THE SOX HAVE THE MAKINGS OF A VERY PRODUCTIVE LOWER HALF OF THE LINEUP

In some ways, it does not come as a great surprise that Jason Bay swatted a pair of homers to propel the Sox to a win on Saturday. It was the 13th time he has had a multi-homer game in his career, and his second with the Sox.

The notable element of his display of muscle was that it came from the sixth spot in the Boston batting order. The fact that Bay – a reliable producer – occupies such a spot gives the Sox a potentially significant advantage over other A.L. lineups.

Last year, no team received more than 29 homers or 106 RBI from its sixth spot in the lineup. The Sox have an excellent chance of exceeding both totals if Bay—who has hit 30 or more homers in three of the last four years—remains in that slot for the year.

Bay was encouraged by his strong few games to start the year. He suggested – incorrectly, as it turns out – that he typically gets off to slow starts.

“I wouldn't write my ticket to the April Hall of Fame just yet,” he told reporters. “It's been nice to get off to a good start. Historically, it hasn't been that good for me."

In reality, Bay’s .276 April average is his fourth best of the six-month baseball calendar, his .388 OBP is second best. Though his .471 slugging mark and .869 OPS are his second worst of any month, the totals aren’t exactly abysmal.

3) IT WILL BE A WHILE BEFORE WE SEE JONATHAN PAPELBON AGAIN

There have been days when Jonathan Papelbon has blitzed through four-out saves with obscene efficiency. Last September, for instance, he went 1.1 innings in just 10 pitches against Cleveland.

There has, arguably, never been a day for Papelbon like Saturday. The Sox closer, summoned to preserve a 4-3 lead with two outs in the eighth inning, did what the Sox asked, but in perhaps the least efficient fashion of his career as a reliever.

After the Sox gave Papelbon a much-needed insurance run in the top of the ninth, he allowed four baserunners (Torii Hunter solo homer, Kendry Morales double, two walks) in the bottom of the inning. He barely escaped defeat when Howie Kendrick, on the 10th and final pitch of an epic at-bat, lined out to right.

Papelbon needed 39 pitches to pick up his second save of the year, a total that he normally reaches over two and even three games. It was the third most pitches Papelbon has ever thrown in relief, and the most since he tossed 42 on August 20, 2006. In 2008, he threw 30 or more pitches just twice all year—once in August, and again on the last day of the regular season.

The Sox are mindful of keeping Papelbon strong through potential October appointments. That being the case, it came as little surprise when Francona told reporters after the game that his closer will not pitch in the series finale against the Angels on Sunday, and may be held out Monday as well.

4) THE MANAGER HAS A LOT OF BULLPEN OPTIONS

There is another side to the story of Papelbon’s extensive usage. Managers often use the initial weeks of the season to determine the roles and responsibilities appropriate to different members of the bullpen. Yesterday’s game suggested that Terry Francona has a great deal of freedom with which to operate.

Because of the well-documented depth of the bullpen, Francona can feel at ease using pitchers such as Papelbon for four-out saves at the beginning of the year. When the Sox closer needs to rest, the team has fallback options with closing experience (Takashi Saito, Hideki Okajima, Manny Delcarmen) available.

Francona’s use of Ramon Ramirez for five outs with the Sox leading by a run further underscored the bullpen depth. The Sox manager said on Thursday that he can use virtually any member of the bullpen in any situation, and that fixed roles were unnecessary. The fact that Ramirez – whose initial two appearances came with the Sox trailing in games – was used to set up for Papelbon illustrated the point.

5) AN EARLY TEST FOR ROCCO BALDELLI

The Sox faced Angels southpaw Joe Saunders on Saturday, marking the beginning of a five-game stretch during which the Red Sox will face four left-handed starters. That means that Rocco Baldelli will be used somewhat liberally, since he entered yesterday’s game with a .296 career average and .838 OPS against lefties, and was acquired primarily to spell either J.D. Drew or Jacoby Ellsbury against southpaws.

Baldelli, subbing for Drew and hitting fifth, went 2-for-4 on Saturday. The Sox plan to have him bat leadoff when he replaces Ellsbury to minimize the disruption on the lineup.

After beating Saunders, the Sox are now 1-1 against left-handed starters this year (the team lost with Scott Kazmir on the hill on Wednesday). A year ago, the Sox were 25-13 in games started by left-handers. Southpaw starters struggled to a 5.77 ERA against the Sox, who benefit not only from several formidable right-handed bats (Dustin Pedroia, Kevin Youkilis, Jason Bay, Mike Lowell) but also from a pair of switch-hitters (Jason Varitek, Jed Lowrie) whose production has historically been greater as right-handed hitters.

Varitek, incidentally, continued his solid start by going 2-for-3 with a double. He also made contact in each of his trips to the plate, and has yet to strike out in his four games this year. That is his longest streak of games without a strikeout since he went five games without whiffing from May 29-June 4, 2007.