At the most superficial level, there's one set of numbers that pop out as indicative of Chris Capuano's last three years in Milwaukee. In each of '05, '06, and '07, he lost exactly 12 games. However, his win total went from 18 to 11 to 5. Ugh.
Of course, the won-loss record is a largely useless way of evaluating a pitcher. We can do a lot better. It seems implausible that Capuano just forgot how to pitch around the all-star break last year; we saw plenty of "good Chris" this year, just not very many outings in a row.
FIP is a good place to start to evaluate pitchers independent of luck and their defenses. In his three 12-loss years, Cappy has had FIPs of, in order, 4.54, 4.05, and 4.44. The National League average this year was 4.44, so Cappy was--for all of the pain that came with watching the games he pitched--precisely average. Given that relievers pitch a little better than starters, Capuano was possibly (a very little bit) above average.
Why, then, are his superficial numbers so bad?
Bad luck (and probably poor defense) had an awful lot to do with it. The answer certainly doesn't come from the batted balls Cappy allowed. He allowed fewer line drives, fewer fly balls, and more ground balls than either '05 or '06. (All good things.) He popped people up at the same rate, and his fly balls stayed in the park at an average rate. Nothing to see here.
One notorious measure of pitcher luck, LOB% (or "strand rate") explains a lot of what went wrong for Cappy this year. I don't want to get into another tired clutch debate, but studies have consistently shown that leaving guys on base (or not) is a matter of luck. In 2005, Cappy's 18-win season, he stranded nearly 80% of runners. This past year, it was below 70%. (That's really low.)
And as was the case with Jeff Suppan, Capuano was probably hurt by the defense. Giving up more groundballs is generally a good thing...unless you're pitching in front of Rickie Weeks and Ryan Braun. Not only that, but think about the groundballs Capuano is like to give up. He's a lefty, so he's going to see a disproportionate number of righties. He doesn't throw hard, so those righties are going to pull the ball. What happens when a righty pulls a ball? That's right: groundball to third base.
If there's one theme developing in these first two post mortems, it's that it takes a heck of a pitcher to do well (as measured by ERA, or Wins) in front of the Milwaukee defense. Someone like Sheets or Gallardo can get enough strikeouts that it may not matter, but that's not the case for Cappy or Suppan. (Or, probably, Vargas, along with the vast majority of pitchers in baseball.) Barring a whole bunch of a position switches and a trade for Orlando Hudson, we need to accept the fact that our back-rotation starters are probably a half-run better than their ERAs suggest they are.
If that's true, Capuano looks just as good going into 2008 as he did going into 2007. That's not great, but it's certainly good enough to be the #4 or #5 starter on a contender. It's also a pretty sweet deal for the $5MM or so he's likely to get in arbitration. As the Suppan deal proves, you simply cannot get production like that on the open market without breaking the bank.
Capuano has been a name floated in plenty of trade talk around these parts, and I would imagine that Doug Melvin will listen when fellow execs make offers this winter. I wouldn't mind parting with him--we probably have the starters to manage without him. But if we do deal him, we need to get solid #4 NL starter value. If some GM thinks Cappy is just "worth a flyer" to be a swing man, that GM should probably go back to shopping at the Ramon Ortiz store.