The Yankees had one of the best bullpens in 2014, but that may not be true again next year.
With a mediocre 84-78 record, and an even more disappointing .478 (77-85) 3rd Order Win%, the 2014 Yankees gave fans plenty to complain about. Their offense was one of baseball's worst, and thanks to a plethora of injuries, their starting pitching wasn't nearly as good as it could have been. But for all that went wrong, there was one area where the Yankees were pretty dominant: the bullpen.
David Robertson turned in yet another fine season in his first year as the team's closer, while Dellin Betances and Adam Warren stepped up in a big way to provide a reliable seventh and eighth inning bridge. Throw in strong showings from Shawn Kelley, David Huff, and Matt Thornton, and the Bombers had one of baseball's deepest bullpens. Only the Royals bullpen -- and their three-headed monster of Greg Holland, Wade Davis, and Kelvin Herrera -- racked up more fWAR than the Yankees squad's impressive 5.9 WAR mark.
After turning down the Yankees one-year, $15.3M qualifying offer, Robertson seems primed to test the free agent waters, leaving the ace reliever's future's up in the air at the moment. Whether or not he'll resign is anyone's guess, but I'll be surprised if the Yankees don't end up with one of the upper-echelon, free agent relievers come Spring -- be it Robertson, Andrew Miller, Rafael Soriano, or Luke Gregerson.
In any event, a bullpen of Betances, Warren, Kelley, and a solid free agent sounds pretty comforting -- without even considering the potential impact of prospects Jacob Lindgren Nick Rumbelow, and Tyler Webb. But while the Bombers collection of relievers looks good on paper, there's no guarantee what this group will put up in 2015.
For one, the Steamer projection system doesn't completely buy into this group's 2014 performance, and forecasts a drop-off from many of the Yankees key bullpen pieces. The system's particularly bearish on Betances, who's 1.40 ERA was the 4th lowest among qualified relievers last season. Steamer has his ERA doubling to 2.80. Still very good, but not lights-out like he was last year. Warren and Huff are also forecasted for ERA spikes of over half-a-point.
Even after accounting for these drop-offs, the Yankee bullpen looks pretty solid. Yet there's yet another reason to be uncertain about this group's prospects in 2015. This one has less to do with the Yankees current crop of arms, but with the volatility of relievers in general. From year to year, there's an awful lot of turnover among the game's elite relievers. The good ones have a habit of falling off the map in a hurry (see: Ernesto Frieri), while elite ones often emerge from unlikely places. The Yankees own Dellin Betances is a recent example of this phenomenon, along with Wade Davis (previously a mediocre as a starter), Sean Doolittle (a converted first baseman), and Neal Cotts (spent four years in exile).
Here's a little example to demonstrate the volatility of bullpen arms. If the Yankees sign Robertson or Miller, they'll have two relievers projected for a sub-3 ERA next year per Steamer. That sounds good and all, but a look at the 21 relievers who were projected for a sub-3 ERA last year shows just how little that actually means. About half of the group fared pretty well --11 of the 21 (52%) logged at 50 innings of sub-3 ERA ball -- but the other 10 either got hurt, posted an ERA north of 3, or both.
The Yankees bullpen was excellent last year, so more likely than not, it'll be good next year as well. But even if they keep all of the pieces in place by bringing back Robertson, there's still a good chance something will go awry, leaving us clamoring for bullpen help come July. Predicting bullpen performance is just that much of a crap shoot.