His FIP (Fielding Independant Pitching) is 4.22. FIP uses only HR , BB and SO to come up with an expected ERA. It assumes a league average BABIP. His xFIP is 4.13. xFIP is similar to FIP but assumes a league average HR/FB. The culprit has largely been his LOB% (left on base percentage): http://www.fangraphs.com/graphs/4635_P_season_full_8_20060814.png That's probably a good thing. We can probably expect Bush's LOB% (and by extention, ERA) to be better next year, everything else qual.