I think he's gotten stronger the more removed from chemo he's gotten. You can see it in his added velocity, and you can see it in his innings and pitch counts. He leads the staff in innings pitched, and he's gone over 100 pitches in 15 of his 17 starts. He's been a horse.
Statistically, he's been much better this year even though his ERA is so high.
2008 - 3.21 ERA, 1.27 WHIP, 2.82 BB/9, 6.50 K/9, .299 BABIP, 3.64 FIP
2009 - 3.87 ERA, 1.29 WHIP, 2.76 BB/9, 10.34 K/9, .342 BABIP, 3.21 FIP
He also mixes up his pitch selection as good as anyone. Only 55% of his pitches are straight fastballs. He throws both his cutter ~once every 5 pitches and his curve ~once every 5 pitches.