When Ervin Santana finished serving his 80-game suspension on July 3, it created an unforeseen logjam with the starting rotation.  Rather than elect to send Mike Pelfrey (or other starters) to the bullpen, it was decided that rookie Trevor May would receive the demotion.  With a 1.8 WAR, May stands as the best pitcher on the Twins MLB roster, so I admittedly was perplexed at the decision to regulate May as a reliever.  The conventional wisdom would say that it is inherent to May’s continuing development that he remain in the rotation for as long as possible.

Now that we’ve seen May in the bullpen for a month, I thought it would be interesting to take a look at his starter vs. reliever splits:

Trevor May, 2015

Starter:     80 1/3 IP, 7.95 K/9, 4.37 ERA, 3.19 FIP, 1.7 WAR, 20.5 K%

Reliever:  11 1/3 IP, 7.94 K/9, 3.18 ERA, 3.26 FIP, 0.1 WAR, 20.4 K%

Wins Above Replacement (WAR) is typically not very kind to a reliever due to the small sample size of innings pitched, which is why May is now “merely” a replacement-level player at this point.  So, we can ignore (but not entirely ignore) May’s WAR value for the time being and still come to the conclusion that May is essentially the same pitcher whether he starts the game, or pitches in the 8th inning.  The value that we want to spend more time focusing on is his FIP.

Fielding Independent Pitching (FIP) is a good way to quantify pitching performance by solely taking into account the types of pitching outcomes that May can control:  strikeouts, walks, hit batters, and home runs allowed.  A pitcher’s ERA takes many things into account, such as poor defensive players and positioning, and research does show that how a ball is put into play is out of the pitcher’s control.  FIP can give us a better interpretation of a pitcher’s performance, and it is to be put into context similar to that of the ERA.

(Side note:  While WAR is league and park adjusted, a pitcher’s FIP is not.  Therefore, if you pitch substantial innings in pitcher-friendly ballparks like Petco Field in San Diego, then you should have a lower FIP than anyone who pitches in Coors Field.  Fangraphs uses FIP- as a statistic that utilizes league/park/playing era adjustments.  I may utilize that in future posts; I might not).

Ok, so if I just said Trevor May is essentially the same pitcher regardless of his role on the pitching staff, then how is his new role the better of the two moves?  Well, we have to dig a little deeper in his metrics:

Trevor May Advanced Metrics, 2015

          HR/FB      BB%     LOB%      FBv

 Starter:   7.1%       5.2%     69.5%   92.2MPH

Reliever: 6.3%        4.1%     82.2%   94.8MPH

These statistics are very meaningful for a variety of reasons.  The Twins’ bullpen ranks 28th in WAR (0.1), 24th in ERA (3.99), 28th in FIP (4.23), and of course, dead last in K/9 (6.23).  While May’s numbers as a whole don’t mean he’s the next Aroldis Chapman, his performance indicators provide improvement to a bullpen that fails to strand runners while giving up a high percentage of home runs per fly balls (10.3%).  You also notice his four seam fastball velocity has risen since being moved to the bullpen.  I have seen it top 96MPH on a couple of occasions, and his average velocity is 3rd best in that bullpen.

So simply put, while Trevor May is probably a B/B- starting pitcher (he would rank 46th in WAR and 34th in K/9 for starting pitchers), he really is only an average reliever in a bullpen full of below average relievers.  May will probably not see another start until September at the earliest when the roster expands to 40 players.  He has shown marked improvement over his first stint in the Majors last August and September, and should be a strong candidate for a rotation spot in 2016.  But with Ryan Pressly (94.3 FBv) just being moved to the 60-day DL, and the trade deadline acquisition of Kevin Jepsen (94.5 FBv) from the Rays, there are very few alternative options to stabilizing a bullpen for the remainder of the season that notoriously lacks power arms.