|Andrew Bailey / Icon SMI|
In each of 2010 and 2011, Bailey allowed 3 homers. They were all solo shots except for a 2-run walk-off homer by Josh Hamilton on 7/9/2011. So that account for just 1 of those extra runs.
The real issue was the fact that he allowed more hits (and more hits for extra bases) in 2011 when runners were on base.
Here were his splits pitching with runners on base:
In few plate appearances in 2011, Bailey allowed 3 more doubles, 1 more triple, plus that homer mentioned above. His OPS+ with runners on was .343 in 2010 and a staggering .757 in 2011.
The good news is that the increased XBH in 2011 were likely due at least somewhat to random chance, as shown by the really high BAbip, and things should regress toward the mean to some degree in 2012....or at least the Red Sox hope that's what happens.