But you want to look at Miller's stats for the last two seasons.
2001: 16-8, 3.40 ERA, 183 K's
2002: 15-4, 3.28 ERA, 144 K's (only 164 innings)
His career ERA is inflated because of a shaky rookie season in 2000, and a couple appearances in 1999.
Here's Buerhle's numbers the past two years:
2001: 16-8, 3.29 ERA, 126 K's
2002: 19-12, 3.58 ERA, 134 K's
As I mentioned, he is not getting the wins this year because the White Sox offense is terrible and providing no run support. Miller plays for a better team, gets more K's and better run support, making him a better option.