As we saw in the last entry, Lester's cutter has been very valuable over the last few seasons. His fastball, however, has been giving him trouble recently. Compare batters' performance off it the last three seasons:
Last year represented a noticeable change in his repertoire. As Lester has shied away from the throwing the fastball as much, he's leaned more on his superior cutter. In 2010, he threw the cutter for 21.7 percent of his pitches, and 22.5 percent to LHB. This is up 9.8 percent over his previous two year rate to all batters, and 14.8 percent to LHB.
Given how successful he's been with the cutter, expect him to continue favoring it over the fastball this season, particularly against lefties.