Luis Severino’s 2023 was an unmitigated disaster. The right-hander did manage to appear in 19 major league games for the second year in a row after appearing in just seven for the Yankees between 2019-21, but he might as well have stayed off the field. Sevy’s ERA and FIP were seventh and fourth worst, respectively, among the 172 hurlers who tossed at least 80 frames this season.
Sevy actually appeared to be returning to form down the line, with a 3.16 ERA over his last five starts, before an oblique injury ended his season. But that late-season improvement goes to show just how bad he was up to that point. It could, however, clue us into what went wrong.
2023 Statistics: 19 games, 18 starts, 89.1 IP, 6.65 ERA, 6.14 FIP, 4.83 xFIP, 18.9 K%, 8.2 BB%, -0.6 fWAR
2024 Contract Status: Free agent
Contrary to popular thought, Severino’s stuff was never all there. Sure, he posted his best four-seam velocity since 2018, but it was still over a tick down from his peak. Plus, velocity isn’t everything; yes, the pitch was a bit harder than in 2022, but it also had nearly an inch and a half less rise. Sevy’s fastball wasn’t flat by any means, yet it went from having nine percent more rise than similar heaters (by velocity and release point) to having just one percent more.
This didn’t change the pitch’s whiff rate all that much, but for a pitcher who throws everything off of their fastball like Sevy (45-percent usage on the pitch in 2023), it meant nothing else was set up quite right. The whiff rates on his changeup, slider, and cutter all fell precipitously, with his slider’s swinging-strike rate dropping a massive 8.8 percentage points. Everything, including the four-seamer, was hit harder, but once again the slider suffered the most, its barrel rate nearly doubling to 12.3 percent.
All told, the four-seamer and slider were Severino’s most costly pitches after being his best in 2022. Their interplay had been crucial to the veteran’s success, but their 20.3-inch vertical separation in 2022 dropped to merely an 18-inch difference in ‘23 not only due to the fastball’s fealty but also the slider’s, which lost about an inch of drop. Sevy may have tried to compensate by locating his heater higher (swiping to the right gives you 2023’s locations):
While keeping his slider locations more or less the same:
But Severino’s four-seamer simply didn’t play at the top of the zone like it used to. Heaters in the upper third cost him 3.3 runs in 2023 after saving him 4.3 the previous season. Per batted-ball event, these pitches were also barreled 6.3 percentage points more often.
Something else you may have noticed from the heatmaps above is that Sevy’s locations were seemingly less pinpointed in 2023. But according to Location+, which looks at expected run value based on where a pitch ended up, Sevy actually graded out slightly better in 2023. Rather, it was his pitch shapes that suffered, which Stuff+ had as going from eight percent better than average (108) to just four percent better (104). The main culprit was his four-seamer, followed by his cutter and slider.
Still, in his last five starts, those three pitches crept back up; his slider even exceeded its 2022 Stuff+. Overall, he ran his repertoire back up to a 107 mark in that span, with a 105 Location+. Sevy may have fired off 13.2 consecutive scoreless innings in that stretch against the lowly Nationals and Tigers, but stuff is opponent-independent; he really looked much more sharp during that time.
Had Severino stayed healthy through the end of the year, he could have gotten that ERA under 6, or dare I say 5. But injury scares are sadly nothing new for him, and despite the occasional flashes, there’s no getting around the fact that Sevy had a simply dreadful season. If this is the end for the former Baby Bomber in pinstripes after being a part of the organization for over a decade, then it’s best to remember the All-Star years rather than the post-Tommy John edition.