For whatever reason, pitchers are the only players assigned the entire team’s wins and losses. Even if a poor defense is the cause of a loss, for instance, the pitcher is still the only one saddled with this negative statistic.
The most accurate way to evaluate how a pitcher’s defense is negatively affecting his statistics is by calculating the difference between a pitcher’s fielding independent pitching (FIP) and total run average (as opposed to earned run average). If there is a significant disparity between the FIP and TRA (aka "total run average"), then a pitcher is undoubtedly being done in by his defense.
Following are the eight pitchers whose statistics are getting slaughtered most by bad team defense.
All statistics and data sourced (through July 21, 2013) from Baseball-Reference.com and FanGraphs.com. Only starting pitchers with at least 70 innings considered. The physical calculation of "FIP-TRA" was performed by me.