Chris Capuano got shelled last night: 4 IP, 8 hits, 6 earned runs. Yeah, it wasn't pretty. This isn't the first time either; hes given up 5 or more earned runs in 7 of his 27 starts, and only once has he gone at least 7 innings in a game in which hes given up 4 or more earned runs. The funny thing about Capuano is that despite all of this, his fielder-independent statistics remain quite solid. His FIP- is 6% below league average (at 106) while his xFIP- is 4% better than league average (at 96). Considering his FIP has always underperformed his xFIP (basically, hes more homer-prone than he should be), I guess you could say hes probably closer to league average or slightly worse rather than a bit above average. But that doesn't really explain the difference between his actual results versus his FIP.Well, for one his BABIP is .312. League average this year is .291. For the traditional fans who disdain this statistic, yeah I know, here we go again with BABIP.... But Capuano's career rate is a dead-even .300 across 940+ innings, and its not likes hes given up more line drives or anything, as his line drive rate this season is actually 2% below his career average. Furthermore, SIERA and tERA are two ERA estimators that take into account balls in play, and both grade out Capuano quite solid for the season: 3.52 and 3.89, respectively. There could just be some randomness to his BABIP, pitchers go through all of the time, even for full seasons (see: James Shields' 2010 season). There is a slight 2% uptick in groundballs for Capuano this season, which have a better chance of turning into hits than flyballs, and the Mets' defense has graded out quite poorly*, so there's a good chance those play at least some sort of role in his BABIP being .12 points above his career average this season.
(*: DRS ranks the Mets 4th from the bottom in MLB, UZR ranks them 2nd from the bottom in MLB.)
And when you dig a little deeper, things start to make more sense. The funny part about his BABIP "struggles" is that they have mostly come in the spot it could hurt him most: with men on base. His BABIP with the bases empty this season is .294. That's quite normal. But with men on? It balloons to .342. That'll certainly hurt the ERA. So now the question is, why is it so high, and is this Capuano's fault? Well, hes not giving up any more line drives with men on, so that's not it. The groundball rate, however? It shoots up 10% with men on. For a pitcher, that is supposed to be a good thing, but this where quality of defense and the fact groundballs turn into more hits than flyballs come into play again, and thus inflate his batting average on balls in play higher than it really should be.
Still don't believe me when I say Capuano has not been very lucky with men on base? Well, compare these men on base issues to his career numbers with men on base. For his career, he has a .296 BABIP with men on base and a 72.5% strand rate, versus a .342 BABIP and 70.7% strand rate this season. That career sample size covers a much larger amount of data than this year, too. Considering all of this, it certainly seems clear that some bad luck has hurt Capuano when it has mattered most -- with men on base -- and it has artificially inflated his ERA. Hes given up a lot more groundballs, which have a better chance of turning into hits than flyballs, with men on base. Again, that's not a bad thing on Capuano's part; its the fact the defense behind him, and probably some general bad luck, that has made him look much worse than he really is.