CLEVELAND — For the first five games — well, four-and-a-half, anyway — of this postseason, the Red Sox offense looked to have finally found its stride.

The Boston lineup diligently worked counts, scored runs in bunched and, in the words of their manager, “kept the line moving.”

Last night, however, the offense’s forward progress came to a screeching halt, stopped by, of all people, Jake Westbrook, who won a grand total of six games during the regular season.

Suddenly, the vaunted Red Sox October offense looked eerily like the one which sputtered regularly during the middle months of the regular season. The one which stranded too many baserunners, squandered too many opportunities and produced far too few runs.

The Sox had just seven hits — all against Westbrook — and only one with a runner in scoring position: Jason Varitek’s homer to right-center in the seventh, accounting for both Boston runs for the night.

In the second inning, the Sox loaded the bases with no outs but failed to score as Varitek popped meekly to shallow left and Coco Crisp hit into an inning-ending double-play to short.

“It was a pivotal point,” said manager Terry Francona of the Sox’ failure to capitalize early.

There was more of the same in the fourth when David Ortiz sliced an opposite-field double into the corner, but then was struck by Manny Ramirez’ batted ball attempting to move between second and third.

The Sox’ last gasp against Westbrook came in the sixth, when Kevin Youkilis singled up the middle and Ortiz drew a one-out walk, presenting Ramirez with a first-and-second situation.

But Ramirez, who came into the game averaging two RBI per postseason game, hit into a double play, the third of the first six innings.

So much for the rejuvenated lineup. Last night, it was turn-back-the-clock time and the Sox looked like they did in June and July.

“It doesn’t much matter comparing (the struggles) to another time of the season,” said Varitek. “We’ve just got to get it done.”

And last night, for a change this postseason, they didn’t.

Since the Sox banged out back-to-back homers off lefty reliever Rafael Perez in the fifth inning of Game Two Saturday, they have scored in just one of their last 15 innings.

“We had some opportunities to change the feel of the game early,” said third baseman Mike Lowell, “and put some pressure on them, especially in that second inning. But Westbrook executed his pitches. He got a lot of ground balls and double plays that helped him out. We’ll go at them again (tonight).”

smcadam@projo.com