BOSTON - Jon Lester's big-league career still is in its infancy.

One thing that has stood out, though, has been the left-hander's inconsistency in the strike zone.

That problem reared its ugly head again last night.

After surviving a first inning in which he issued a first-pitch ball to three of the four batters he faced, Lester pounded the strike zone in the second. Of his 14 pitches in the inning, 13 were strikes.

That ratio took a beating over the next two innings, particularly in the fourth, when Lester was tagged for four runs, including a two-run double by Edgar Renteria and a two-run homer by Marcus Thames. Those big hits followed a pair of walks, two of four free passes issued by the left-hander.

And when you're not throwing strikes, you don't get any borderline calls, either. Lester barely missed with breaking balls on 1-and-2 and 2-and-2 pitches to Thames before the Tigers' left fielder unloaded on another breaking ball for his homer into the Monster Seats.

Lester went to three balls on 6 of the first 19 batters he faced through the first four innings. And he was unable to put away the Tigers hitters, failing to record a strikeout. Carlos Guillen had a seven-pitch at-bat (hard groundout) and a nine-pitch at-bat (walk). Thames' homer came on the ninth pitch of his at-bat.

It was not an easy night to pitch weather-wise, but Lester's inconsistency in his 5 1/3-inning, 97-pitch (60 strikes, 37 balls) outing last night can't just be explained away by that factor.