Jon Garland has been stuggling this season. One of the reasons is slightly hidden. When Garland has pitched the day after Dan Haren and against the same team Haren pitched against, he is 0-7. Dan Haren has dominating and nasty stuff, while Garland has the same type of pitches, he just isnt as good with them. So the effect we have going here is teams are seeing Haren on the first day and he is throwing 95 mph fastballs (and cutters) along with his nasty splitter, and occasionally changeups and curveballs. The next night they face Jon Garland who is throwing the same fastball (and cutter) just 10 mph slower. Garland also features a slider that is slower and has similar break velocity to Haren's splitter.
Long story short, Jon Garlands numbers are a bit skewed by the fact that teams are basically getting to see the same pitches the night before, just much slower and less effective the next night. When Jon Garland has NOT followed Haren against the same team, his teams record this season in 6-3.
I expect Garland to have better success tonight than he has in his last 8 games (where 7 of them were after Haren).