Josh Fields is a very bad baseball player. In 2007, he was a 1-tool player; he hit for power. Now, he doesn't even do that. Crede was an excellent defensive 3B who had a lot of back injuries and consistently hit for power.
I believe Jenks is on the decline. His velocity isn't what it used to be. In the past, he threw a heavy ball, but he gave up a lot of long balls this year. His 1.5 HR/9 in 2009 is terrible.
Vazquez is an NL pitcher. He was mediocre in New York and Chicago. The Cell is definitely a hitter's park, but guess what? Vazquez was actually worse on the road in 2006, 2007, and 2008 with the Sox. Check the splits.
No pitcher does well at home in Chicago? How about Buehrle (3.70 ERA, 1.249 WHIP), Floyd (3.57 ERA, 1.143 WHIP), Danks (3.66 ERA, 1.183 WHIP in 2008), Esteban Loaiza (3.32 ERA, 1.217 WHIP in 2003), Bartolo Colon (3.84 ERA, 1.151 WHIP in 2003), Jack McDowell (3.55 ERA, 1.276 WHIP), Jon Garland (4.15 ERA, 1.313 WHIP), Alex Fernandez (3.51 ERA, 1.171 WHIP), Wilson Alvarez (3.83 ERA, 1.381 WHIP), and Mike Sirotka (4.02 ERA, 1.363 WHIP). Even Vazquez pitched well at the Cell in 2007 (3.57 ERA, 1.099 WHIP).