It's immediately apparent, seeing DK's PBC Blog post this morning, that Octavio Dotel and Matt Capps are going to be compared to each other all summer in Pittsburgh. Because I don't know what Capps wanted in arbitration (as I've said before, based on his salary and what guys like Heath Bell are settling for, I'm guessing he would've asked for at least $4 million, or maybe a little more) or what he would've been willing to settle with the Pirates for (it might've been the $3.5 million he signed with the Nats for, but seeing all of your offers laid out in front of you in free agency is different than negotiating with one team), I don't know if I'd compare their salaries straight up, but the general sentiment that the Pirates swapped two years of Capps as closer with two years of Dotel is a fair enough concept.
As someone who's not sure we'll ever see the Matt Capps of 2006-2008 again, I'm willing to make that swap (though, again, I have my reservations about the way the team disposed of Capps, but I'm pretty tired of talking about that at this point). That said, I do have some reservations about Dotel that I think are worth talking about, especially since we're more or less immediately installing him as the closer.
The first two points are ones brought up by BP's Christina Kahrl in her Transaction Analysis Blog (link is subscriber's only): Dotel had a terrible left/right split last year (righties OPS against him was .652, lefties were 1.000) and he's an extreme flyball pitcher (his GB/FB last year was 0.58, which is close to his career 0.64). Generally, Dotel's right/left split is pronounced, though not nearly as much as it was in 2009. His career split is .660/.735, which is close to his 2008 numbers (.654/.764).
The next point springs from his proclamation that he wants to get back to throwing more fastballs than the 82-84% he threw with the White Sox. That's not necessarily a bad thing, but FanGraphs valued his fastball as below average last year for only the second time in his career while rating his slider as his out pitch. The PitchFX numbers, which I admittedly haven't charted out on my own to visualize the comparison between the 2008 and 2009, see more horizontal break on his fastball in towards right-handed batters. This theoretically could explain the reason lefties pounded him in 2009. This requires further investigation, of course, but it's a hypothesis.
At this point, you can probably see where my concerns lie. Diminishing fastball + weakness against lefties + lots of flyballs = untucked shirts. The question that remains is whether or not those tendencies, which were more pronounced in 2009 (except for the flyballs, which he's always given up a lot of), are part of the generally fluctuating reliever performance or if they're a sign that Dotel is starting down the aging curve. Even if he's starting to show the effects of aging I think he can still be an effective reliever, but he might be better suited for a role that allows Russell to get him into favorable matchups rather than the straight closer's role.