Hunter's K/9 rate was 6.8 in his early years, he was never a power pitcher. You still totally forget to include his absolutely dreadful last four years of his career.
Oh, his ages in the seasons you include were: 27, 28, and 29.
Try again. His best year was in 1968, when he fanned over a batter an inning.
Both of these pitcher both pitched in a pro-pitching era, anyway.
About a batter per inning, but Halladay wasn't the strikeout pitcher that Oswalt was.
K/9 rates
2001 - 9.15
2002 - 8.03
2003 - 7.63
2004 - 7.82
2005 - 6.85
2006 - 6.77
2007 - 6.17
Seven years.