I read in Clay Rapada's scouting report in the 2008 Baseball America Handbook that he struggles against right-handed batters. Thanks, to MinorLeagueSplits.com, I was able to confirm this. I'll conclude that under no circumstance should Clay Rapada face a right-handed batter in a close game. Here are his splits from AAA Iowa last season.
vs. R: .341/.400/.496
vs. L: .125/.272/.188