After Neal Huntington's offseason bullpen spending spree, most of the Pirates bullpen is locked up before the season even starts. We've got two holdovers in Evan Meek and Joel Hanrahan, two new additions almost assured of spots in Octavio Dotel and Brendan Donnelly, and two new signings that are pretty safe bets to make the team in DJ Carrasco and Javier Lopez. That leaves, at the absolute most, one bullpen spot left. Actually, without a Rule 5 guy in the pen it might leave zero spots. That said, I think they're going to roll with seven in the 'pen enough to dedicate an entire blog post to it.
Depending on how you look at it, there's anywhere between one obvious choice and an endless run of potential arms here. If we go straight up with the best pitcher, the last reliever should be either Kevin Hart or Dan McCutchen. The problem is that they're both way too good to be a seventh reliever. They both have to pitch and they both have options left, so there's a really good chance that whoever loses the competition for the last rotation spot ends up in Triple-A to await an injury and a second chance.
Without Hart or McCutchen in the competition, things get crowded for that last spot. Between guys on the roster (Chris Jakubauskas) and NRIs (Jeff Karstens, Steven Jackson, Brian Bass, Brian Burres, Vinnie Chulk, Wil Ledezma, maybe Jack Taschner or one of the other guys in camp) the Bucs have options. Which one seems like the best?
I'd guess that the seventh reliever will either be someone with the ability to chew some innings up, or a lefty/righty with reverse splits. Donnie Veal might have the ability to do both, but he's got to go to Triple-A to start the season, even if he has an awesome spring. But besides Carrasco, no one from the first paragraph can really be a long-man. In fact, with Dotel and Donnelly's age and arm problems, it'll probably be rare to see either pushed past one inning. And of course, Lopez is the only lefty currently in line for the bullpen and without Jesse Chavez, the Pirates don't have a lot of guys to mix and match with.
EDIT (3:51): I sort merged Brian Burres and Brian Bass in my head when I wrote this; I've changed it around to reflect that there is someone named Brian Burres in the running here. The conclusion doesn't change much, though, beyond me getting Burres' name right. Thanks to SyrBucco in the comments for straightening me out.
Those two criteria don't eliminate many guys from our first list; Jakubauskas, Karstens, Jackson, Burres, and Bass have all started at least fairly recently and Burres, Taschner, and Ledezma are lefties. Chulk is probably out as a guy that it would've been worth giving a shot to before all of the signings. Actually, Taschner and Ledezma are the next two out; neither pitched particularly well last year and both would probably do more harm than good in the bullpen. That narrows the list down to four.
Jakubauskas is the only guy left in the running that's currently on the 40-man roster. It's a safe bet that Neal Huntington likes him if he went out and claimed him after he and his staff presumably scouted the Mariners' system extensively during the Snell/Wilson trade. His journey from the independent Frontier League to the Majors makes him hard to judge since he was much older than his minor league competition, but he was excellent in splitting time between Double-A and Triple-A in 2008. He also showed a reverse split in the minors, which could help against lefties, except that he got bashed by lefties with the Mariners last year and as Wilbur Miller points out, it's pretty strange to see a righty with a curveball for an out pitch and a reverse platoon split.
In Karstens, we all know what we have in a decent enough long-relief/swing guy who probably shouldn't be put into close games. Bass is really pretty similar, maybe with slightly better recent minor league numbers. The same goes for Jackson; he put up a nice enough ERA, but his sinker doesn't get enough ground balls nor does it create any reverse-platoon split and so he's not much more than adequate. Burres is the only one that's both an inning-eater and a lefty, but his Major League numbers are rough so far. His Triple-A numbers from last year weren't great either, but it was for Las Vegas in the PCL and his rates were OK, so he could be someone to keep an eye on.
In the end, this decision might not come down to who the best pitcher is. The Pirates still have a bunch of options on Jakubauskas (if they don't DFA him to make room for someone else) and could send him to Triple-A to work as a starter or get some real work out of the bullpen while Burres makes the team as the seventh reliever to fill in the gaps that Carrasco and Lopez can't. If I had to guess right now, I'd say it'd be one of these two (Burres or Jakubauskas), but there's certainly a lot of room for competition in camp here and if Donnelly or Dotel or Lopez or Carrasco doesn't come into camp in shape or someone gets hurt, there might be more than one spot up for grabs.