He converted to the pen in 2005. When he was in the pen that yr, he was dominant.
2006 he was average, with a high 4's ERA but more than a K per inning and a WHIP of 1.33.
2007, he was dominant, lights out.
2008, he got hurt and wasnt effective
2009, he missed with arm surgery
2010, he was dominant to a ridiculous level.
As a reliever, he has shown he has the stuff and has proven he can be effective. His last 2 full seasons as a reliever, he's had an ERA in the low 2's and a WHIP around 1 with well more than 1 K per 9IP. Deny it all you want, but he has closer stuff and has shown the capacity to put up closer numbers