We wouldn't be so lucky as to have the season start tomorrow. If it did, though, the bullpen would look like this:
LR R Lance Cormier
MR L Randy Choate
MR R Dan Wheeler
SU R Grant Balfour
SU L J.P. Howell
CP R Rafael Soriano
Those guys are basically locked in. Maybe R.J. Swindle knocks Choate off the wagon, but that seems unlikely to happen before opening day. That leaves that final middle relief spot - which is really more of a mop-up role - up to a slew of internal and external candidates. The obvious internal names are as follows: Winston Abreu, Jeff Bennett, Andy Sonnanstine, and Dale Thayer; while the external list is a bit 302.more complicated. Kiko Calero is still out there, as is Russ Springer, and even Chan Ho Park.
The point I want to make here isn't about the name or specifics. It's simply that whoever wins the spot won't matter too much. The Athletics had the best pen in baseball during 2009. Their top four highly-leveraged relievers were Andrew Bailey, Michael Wuertz, Brad Ziegler, and Craig Breslow. Number five was amusingly Springer, who had a below average leverage index and pitched in 40-odd innings. Same thing with the Boston Red Sox.
The New York Yankees actually had six relievers with a higher than league average pLI and more than 20 relief appearances, but one of those was Brian Bruney and another was Damaso Marte who pitched 13 innings in 21 appearances. The Braves only had three - Soriano, Mike Gonzalez, and Peter Moylan - and they ranked second in pen FIP. Here's how the other teams stacked up:
Even if you break it down by FIP rank and league, it still comes out to teams using about 4.5 relievers with leverage indexes higher than league average. Even in 2008, the Rays had only five relievers. Currently they have four (five if you count Choate) guys who should fit this bill. Unless it's a Ho Park type, don't expect the final pen arm to get too many reps when the game is on the line.