Looks like Billy Koch is being demoted from his closer role with the White Sox.

On the heels of his most recent mound misadventure, Billy Koch appears to be out as White Sox closer.
Koch, who served up a game-winning, 3-run homer to the Devil Rays’ Carl Crawford in the ninth inning Friday, hopes that’s not the case.
“I think that’s extreme,” Koch said Saturday. “I know how to get the job done. And I will get the job done. I’ve gotten the job done in my career 85 percent of the time, or whatever the number is. I consider that being pretty (darn) successful.

It that really being successful? Koch came up in 1999, and between 1991 and 2002 the ML save percentage was 67%. However, that’s not the right number for comparison. Middle relievers tend to get blown saves without the chance for the corresponding save to offset. So, let’s just look at closers; pitchers who have had 20 saves in a season. The save percentage for this group was 85%. Billy Koch over that time was 86.2, a little better than average. Keith Foulke was 86.5, ranked just about Koch. So Koch was pretty much an average closer.
So the trade looks like another great deal for Billy Beane. As Jim Callis said in his analysis of the trade at the time:

Though Koch set a career high for saves in 2002 while Foulke had his worst season since becoming a closer, Koch has been a bit overrated while Foulke has been underrated. Koch throws 5-7 mph harder than Foulke, but Foulke has been more statisically dominant, averaging fewer hits, fewer walks and more strikeouts per nine innings than Koch over the course of their careers.

Buy low, sell high. Koch has a career K/BB of 2, while Foulke is near four. Beane will let him go at the end of the year, and use the compensation draft pick to improve his depth, and go out and find another decent closer. Pretty impressive.