BALTIMORE — While speaking on Tuesday about his club, Red Sox general manager Theo Epstein could not help but admit that his team’s starting rotation had not quite been what the team had envisioned entering the season.

“I think it’s fair to say that we expected the rotation one-through-five to be a real weapon for us, that if everything broke our way might be really dominant in that there was even some margin for error built in. If one guy didn’t perform we had the horses to pick up the slack. And it hasn’t come to fruition exactly the way we imagined,” said Epstein. “It hasn’t all come together the way we would have liked, and that’s baseball.

“You try to put the pieces in place and hope it plays out a certain way, but it doesn’t always work that way. There’s still time to sort of right the ship and string together quality start after quality start after quality start and figure things out for the future as well. I think we certainly have the talent. We have as talented a starting rotation as any team in baseball. It’s just been one of those years where we havne’t had the consistency and the consistent domination I think one through five that we had the potential to have, I think unfortunately.”

On Thursday, Daisuke Matsuzaka turned in a performance that was emblematic of his rotation. He made it through three innings without allowing a hit, and sailed through five shutout innings. And then, in one monstrous inning, things came apart, as Matsuzaka allowed four runs on four hits and a walk.

It was still good enough for the Red Sox to claim a 6-4 victory against the Orioles, but it was a reminder of one of the great riddles of the Sox season. On many occasions, starters have delivered a tease, flashing dominant stuff but then seeing the excellence unravel like a ball of string in one or two innings. Matsuzaka is 9-4 with a 4.29 ERA, yet like colleagues Josh Beckett and John Lackey, there remains a sense that he could have done more.

WHAT WENT RIGHT FOR THE RED SOX

–Once again, Matsuzaka offered a glimpse of the stuff that has re-established him as a power pitcher this year. He operated primarily with a 92-94 mph fastball that ticked up to 95 on a few occasions. He has become a pitcher who now can succeed with blunt force, chiefly with a a fastball, cutter and his sharp slider.

Though he lost his shutout bid in head-spinning fashion in the sixth, he still proved effectively aggressive. Matsuzaka attacked the strike zone for much of the night, worked at an efficient pace with the bases empty and walked just the one batter in the sixth. The contest marked just the fourth time in his 20 outings that he had walked fewer than two in a game.

–Adrian Beltre reached the 25 homer plateau for the fourth time in the last five seasons. He and Alex Rodriguez are the only third baseman in the big leagues to reach that milestone in four of the last five years.

–Scott Atchison turned in an excellent relief outing, striking out three and retiring all six batters he faced.

–The Sox knocked out starter Brad Bergesen after he threw just 5 1/3 innings. Boston is now 40-25 in games when the starter pitches fewer than six frames.

WHAT WENT WRONG FOR THE RED SOX

–For the fifth time this year, Matsuzaka allowed four or more runs in an inning. Only Tim Wakefield (6) has been victimized for more such rallies.

–Victor Martinez went 0-for-4, ending a seven-game hitting streak in which he’d gone 13-for-30 (.433).

–The Yankees won again. The Red Sox have not been able to make up any ground in the division race in five games.