Last season, the Rays' bullpen ran into a world of pain during the final few months of the season. While the pen was no less talented than the well-performing 2008 group, the results did not work out quite as well. Many, including myself, were searching for answers beyond simply accepting the performance as bad luck. For a recap of my work, check out Quantifying Bullpen Management and One More Crack at Dissecting Bullpen Use.

There is reason for optimism this season as the overpaid elder-statesmen Troy Percival, Chad Bradford, Russ Springer, Jason Isringhausen, Joe Nelson and Brian Shouse have been replaced by Rafael Soriano and a Player to be Named Later. 

Given the frequent calls to the bullpen to the last year, I thought it might be interesting to figure out optimal roles and usage. Let's take a look at how the current crop of six relievers' career splits with the bases empty and with men on.

Observations:

-As a long time supporter of Grant Balfour as the designated mid-inning firefighter, I was quite surprised to see the difference in his performance when runners are on base. The approximate 9% decline in strikeout percentage and .106 increase in .SLG against were quite striking. His numbers remain competitive with most of the rest of the pen, but he has not beasted the way he does with nobody on. Fewer strikeouts and not many ground balls may not be the best recipe for a firefigter.

-Given Balfour's superiority with no one on, it seems a good fit to put JP back in the premier firefighter role when the leverage gets cooking. He succeeds against hitters of both hands and induces a high percentage of ground balls. Balfour could be one of the better 8th inning guys with JP cleaning up messes if he wasn't needed earlier. If JP has not been used, they could play the matchups with JP and Aussie. 

-Dan Wheeler has continued to retire batters or allow home runs. I've never been shy about stating Wheels should only pitch with the bases empty or slap-hitters at the plate. Wheeler should be an early middle reliever. If its a tight spot with men on, Cormier makes a solid option to clean up. I'm a little leery of his low slugging percentage against with men on. There seems to be no explanation for slugging to be inverse with men on base. With a 50%+ career ground ball rate, the double play is far more likely for Corms than any other reliever not named Howell.

Randy Choate will continue to come in to face the tough lefties. This is non-negotiable.

Rafael Soriano has the 9th inning ice water in his veins. With nearly identical dominating splits,Rafa does  not buckle under the pressure of base runners. The Rays are paying him a lot of money and have traditionally used a 9th inning closer under Maddon's watch. While he could excel in a highest leverage role, its unlikely he will do anything other than come in during the 9th inning with a lead and shut opponents down. With our newfound bullpen depth and a roving J.P., I can live with that.