Unless you’ve stumbled upon this post by accident or have a particular passion for bullpens — particularly for teams with not particularly great bullpens — you are familiar with the positional power rankings here at FanGraphs. The position players were all covered last week, so don’t forget to read up on any you might have missed. Jeff Sullivan wrote a useful introduction that is also available among the links above.
I haven’t actually looked into this, but I would have to guess that these relief rankings are subject to the most volatility when it comes to how relievers actually play out by the end of the season. Jeff Sullivan recently noted the lack of consistency of bullpens from one year to the next. One could also look to last year’s rankings to make that point. The Arizona Diamondbacks were projected to finish last in these rankings a year ago, however, they finished 11th in 2017 reliever WAR. In addition to the Diamondbacks, the Angels, Blue Jays, Brewers, Phillies, Rays, and Royals were all featured in the bottom half of last year’s rankings and ended the season in the top half by WAR.
Part of the uncertainty is due to how closely these projections are bunched together. The third- and 27th-ranked bullpens are separated by a little over two wins. One or two good (or bad) performances can have a pretty big effect. Midseason trades can also play a major role, as bad teams with good relievers end up having bad bullpens in the second half after trading their good relievers in July. Try not to get too hung up on any particular ranking or projection. Relievers are already frustrating enough.
Craig Edwards can be found on twitter @craigjedwards.