One of the biggest Red Sox strengths over the first three months of the season has become a pronounced weakness in July.

In April, May and June, the Sox beat left-handers like a drum. But this month, the team has suffered a reversal, creating a particularly perilous stretch of the schedule as the Sox are amidst a run of facing left-handers in four straight contests.

The first such game did not go well. On Tuesday, the Sox had their opportunities to blast Oakland starter Dallas Braden out of the game in the first couple of innings. It was precisely the sort of opportunity that Boston took advantage of time and again in the first few months of the year.

But on Tuesday, after the Sox amassed a startling seven hits through the first 11 batters of the game against Braden, they could do no more. The Sox scored four runs thanks to some Oakland defensive miscues in those first two innings, but Braden settled from that point, and the Sox never scored again in their eventual 5-4, 10-inning, walkoff loss. (Recap.)

Braden received a no-decision, as the Sox continued their recent struggles against left-handed starters. In 25 starts through the end of June, southpaws owned a 5-8 record and 5.86 ERA while allowing the Sox to hit at a .272 clip. They averaged barely five innings.

In six starts against Boston this month, left-handed starters are 3-1 with a 2.65 ERA and .243 batting average against the Sox. They have pitched, on average, a bit more than six innings an outing, contributing to their teams’ overall 4-2 record in those games.

Naturally, part of that is a reflection of the quality of pitchers that the Sox have been facing. Their struggles have come against a group that includes two All-Stars (Cliff Lee and David Price), a pitcher who tossed a perfect game (Braden) and three young pitchers with tremendous stuff (Ricky Romero, Brian Matusz and C.J. Wilson).

Even so, the Sox are clearly a less imposing group against left-handed pitchers this month than they were through June. In that regard, the absence of Victor Martinez (who was hitting .431 with a 1.266 OPS against lefties) has been particularly painful. (Surprisingly, Dustin Pedroia has struggled against lefties this year, hitting .229 with a .685 OPS against them.)

The road remains very left-handed for the Sox in the next few days, when the team will face left-handers Gio Gonzalez, Ryan Rowland-Smith and Jason Vargas. Clearly, the team will need to solve southpaws in the coming days in order to make up any ground in the playoff hunt.

Here are a few other noteworthy developments from Tuesday’s game:

WHEN OPPORTUNITY CAME, WAKEFIELD STRUGGLED

Tim Wakefield’s name is splashed across the Red Sox’ career leaderboards with good reason. The 43-year-old has been a source of stability for the Sox for the better part of 16 years, time and again delivering exactly what the club has needed.

Yet in nearly two months in the rotation following a back injury to Josh Beckett, he proved less than stellar. The knuckleballer was unable to reproduce the tremendous form that earned him an All-Star berth in 2009.

Since Beckett landed on the DL, Wakefield has made 11 starts, going 3-6 with a 5.75 ERA. Among the 134 big league pitchers to throw at least 40 innings in that span, Wakefield ranked 119th in ERA.

On Tuesday, his knuckleball had incredible movement for most of his outing. For the most part, he kept Oakland completely under wraps. Yet his lone inning of struggle proved particularly costly. Wakefield allowed four runs in the third inning, a frame in which the pitcher’s command faltered just enough to cost him a chance at Sox history.

Had Wakefield won, he would have become the oldest Sox pitcher (43 years, 352 days) to claim a victory. Instead, Dennis Eckersley remains in possession of that title, having won a game at 43 years, 349 days.

There is a good chance that Wakefield will still set that record, but it now becomes something of a guessing game as to when he might do so. With Beckett and Clay Buchholz both poised to return, the knuckleballer will return to the bullpen. It is a role in which he takes little joy, and yet, given his performance this year, it would be difficult to say that the Sox have any other course of action but to move the knuckleballer out of the rotation.

DREW DISAPPEARS

In his first two games of July, J.D. Drew looked like he might emerge as a lineup force to help carry the Sox in the absence of several lineup mainstays. He slammed a pair of homers on July 2, then went 3-for-3 while driving in a pair on July 3.

In 13 games since then, however, Drew has done little from the middle of the Sox lineup. After going 0-for-4 on Tuesday, he is hitting .182 (8-for-44) with a .229 OBP and .273 slugging mark. After striking out twice on Tuesday, he has punched out in a quarter (12 of 48) of his plate appearances in this stretch.

Drew is capable of being an impact bat, but at a time when his team would have benefited greatly from one of his hot streaks, he has done little. For the year, he is now hitting .270 with a modest .820 OPS.

NO BULL – THE ‘PEN HAS BEEN PRETTY GOOD

Yes, newly minted reliever Michael Bowden was the man on the mound when the Sox suffered their walkoff loss. He was the pitcher who left a fastball up and over the inner half of the plate that Kevin Kouzmanoff whacked with an inside out swing for the game-winning single to right.

And it was Ramon Ramirez who suffered the loss, set in motion by a one-out single followed by a balk that was called by home plate umpire Bob Davidson.

Still, the Sox have received some positive signs that their bullpen may have some avenues to internal improvement. As a group, Red Sox relievers have a 1.75 ERA in their last seven games.

Perhaps the most encouraging bullpen development for the Sox has been the return of Manny Delcarmen. He allowed 11 of 14 batters to reach in his final three appearances of June, a struggle that led to his placement on the disabled list with a forearm strain.

Since returning on Saturday, he has retired all seven of the batters he’s faced. On Tuesday, he pitched 1 1/3 perfect innings. If he is able to reclaim his spot as a reliable presence in front of Jonathan Papelbon and Daniel Bard, Delcarmen could represent a bigger upgrade to the Sox bullpen than anything that might be available on the trade market.

THE CAVALRY IS COMING?

Clay Buchholz will be back on the mound on Wednesday following his spell on the sidelines with a hamstring strain. Josh Beckett will join him in the Sox rotation on Friday, restoring to the Sox one pitcher who was expected to anchor the pitching staff in 2010, and another who pitched like an ace in the first half.

Jed Lowrie joined the Sox on Tuesday, in anticipation of being activated from the disabled list prior to Wednesday’s game. If he can remain healthy, he could provide the Sox with a far more versatile roster, giving the Sox their best middle infield alternative to either shortstop Marco Scutaro or second baseman Dustin Pedroia.

Jeremy Hermida, who went 1-for-4 for Triple-A Pawtucket on Tuesday, is slated to rejoin the big league club on Thursday.

Victor Martinez, meanwhile, appears to be getting closer to games, having taken batting practice on Tuesday and also doing some catching work while wearing a protective splint on his left thumb, which suffered a small fracture in late-June. Manager Terry Francona told reporters that there is a chance the catcher could return to the lineup before the end of the road trip.

For a team that has seen an assembly line of players head to the disabled list in recent weeks, the beginning signs of a movement in the opposite direction will no doubt come as welcome.