A’s Add Trevor May With Eye Toward July

Last Friday, the Athletics signed right-handed reliever Trevor May to a one-year, $7 million deal. He joins Aledmys Díaz and Jace Peterson as short-term veteran signings for the rebuilding A’s, but while Díaz is coming off of a fairly typical season for him and Peterson is coming off of his best, May will be looking to rebound after a poor 2022 showing.

Given that the A’s still have a ways to go before entering competitive territory again, one of the motivations behind these signings, besides obtaining more mentors for the up-and-comers, is likely to provide trade deadline fodder. Díaz and Peterson will most likely draw some interest if they retain their current levels of performance; the former has been around a 100 wRC+ for quite some time now, and the latter has had a few decent years at the dish and could increase his value further by cementing his gains with the glove. Either way, the floor is relatively high for these utilitymen, but their range of outcomes is narrow. May, however, has the potential to be either a non-factor or quite valuable come July.

Chosen in the fourth round of the 2008 draft by the Phillies, May was dealt to the Twins a few years later along with Vance Worley in exchange for Ben Revere. He would go on to debut as a starting pitcher in Minnesota after putting up a 2.84 ERA across 18 starts for their Triple-A squad in 2014. After a tough first appearance in the majors and a middling subsequent relief outing, his next 23 appearances (spanning 2014 through mid-’15) were all starts. During that time, he ran a 5.40 ERA despite a 3.76 SIERA backed by stellar 21.2% and 5.8% strikeout and walk rates. Among the 110 hurlers who threw at least 100 innings during that stretch, his 1.77 ERA-FIP separation was easily the largest. But at .352, his BABIP was the second largest, underscored by a 30.6% hard-hit rate that tied for 21st and an above-average line drive rate tied for 38th.

Whether regression would have come for the starter version of May, we don’t know, as he was moved to the bullpen. But his four-seamer, which he threw 48.9% of the time during that 23-start stretch despite the pitch costing him 3.1 runs, immediately saw a velocity increase, validating the Twins’ decision regardless:

Game 26 was his first as a reliever, as you might be able to tell by the narrower and higher velocity band. All told, the pitch went from averaging 92.1 mph to 95 the rest of 2015. He threw it 54.8% of the time and it saved him 4.3 runs, easily besting his other offerings. His BABIP remained high at .337, but his swinging-strike rate jumped nearly four points to 13%, and his K-BB% jumped six points to 21.4%. His hard-hit rate also dipped to 26%. Those improvements brought his ERA down to 3.15.

The next year, May pitched exclusively out of the bullpen. He was dogged by some misfortune, such as a lowly 66.4% strand rate, which caused his ERA to balloon to 5.27. But he maintained his strikeout and velocity gains, punching out 32.1% of hitters and averaging 94.5 on the heater. On the heels of that performance, he actually competed for a rotation spot before the 2017 season but unfortunately sustained a UCL injury that forced him to undergo Tommy John surgery.

He returned with a vengeance in the second half of 2018, notching a healthy 15.4% swinging-strike rate and a superb 30.1% K-BB%. His velocity stood at 94.0 mph, as he was ostensibly still not 100% healthy; the next year, pitching at full strength, his velo jumped once again, this time to 95.5. The idea that velocity increases on average after Tommy John surgery is a myth; in fact, for pitchers who have the surgery when they are between 25 and 29 (as May did), velocity significantly decreases on average, making him an outlier in this regard.

Not only did May defy trends with his speed surge, but his fastball also became one of the best in the bigs as a result. The first year of the surge, in 2019, his fastball saved him a whopping 16.9 runs. That season stands out as the 19th best among all 1,234 reliever four-seamer seasons (min. 60 innings pitched) since the pitch-tracking era began in 2007. Further, since its last jump in 2019, his four-seamer has been the whiffiest in baseball; among the 369 pitchers with at least 750 four-seamers thrown over the past four years, his ranks first with a 16.3% swinging-strike rate. And he’s thrown 1,827, so he has over 1,000 to spare for that leaderboard.

What separates May’s four-seamer from the pack? Despite all I’ve made of his velocity, which peaked at 96.5 in 2021, its 96.2 average over the past four seasons only ties it for 53rd hardest on the above leaderboard. May gets good extension, so his effective velocity on the pitch stands at 21st, but that’s still not enough to make it stick out. The movement is only slightly above average too, as the pitch notched 7% more rise and 3% more run than four-seamers with similar velo. Is his fastball truly unremarkable despite its whiffiness?

The x-factors for May’s fastball might be his two plus secondaries, vestiges from his time as a starter. Since 2019, he is the only of 160 pitchers to have at least a 15% swinging-strike rate on both his changeup and four-seamer (minimum 750 four-seamers, 400 changeups). He actually exceeds 16% for both: 16.3% on the four-seamer and 16.7% on the change. The two pitches have a spin-axis (below left) that differs by just 15 minutes or 7.5 degrees, yet their movement (below right) differs by a wider margin, suggesting their potential to work in tandem:

What’s more, the velocity gap between the two has been increasing. As I detailed in my last article about Noah Syndergaard and his new contract, velocity doesn’t decrease uniformly across a hurler’s offerings. As for May, his pitches didn’t speed up uniformly:

The current version of his fastball/change combo has the largest (and therefore best) velocity gap. But what’s going on with the slider? Its velocity gains outpaced the four-seamer’s by 1.2 mph after the first jump, but then it lost 1.9 mph the next time the four-seamer surged. The pitch grew firmer after the first jump, losing both drop and cutting action, so perhaps May made a change in order to increase the movement again:

Despite the increase in drop to career highs, May’s slider still lost cut going into the last timeframe, leading me to believe that the shift was actually more about regaining the velocity gap between it and his four-seamer. Plus, the slider’s performance has tracked better with velocity gap than with movement (it had the most movement during the first timeframe):

May’s slide-piece has actually become his preferred secondary. He used to mix in a curveball and two-seamer earlier on, but both offerings cost him 1.2 runs per 100 tosses, and he had virtually scrapped them by 2020. Since then, he’s utilized the slider more than a quarter of the time, with the change checking in at a 15.5% usage and the rest going almost entirely to the four-seamer.

With his repertoire polished and his velocity gains cemented, what went wrong for May in 2022? In the month bearing his name, he learned that he had been pitching through a stress reaction in the portion of his humerus bone near his elbow. The injury, which an experiment with a split-change may have contributed to, had been causing him pain since the beginning of the season. As a result, he coughed up eight runs in 8.1 innings. After returning in August and shelving the split-change, he allowed just six runs in 16.2 innings the rest of the way with a 35.7% K-rate. This despite worse fastball command than he’d averaged, which might be chalked up to rust. Below left, through the dog days of the 2022 season, he missed high with the heater far more often than in his career (below right):

If he remains healthy — a sizable “if” for a now–33 year-old with multiple serious arm injuries in his past — May should be Oakland’s most valuable player available at the deadline. He seems poised to bounce back, especially if he regains his fastball command and stays off the IL. For the stretch run, what contender wouldn’t trade a prospect to shore up their bullpen with one of the best fastballs in the league?