The New York Mets began their offseason hunt for starting pitching by snatching up Luis Severino on a one-year, $13 million contract. After a rollercoaster season that led to -0.6 WAR, Severino had no choice but to take a prove-it deal and hope his performance in 2024 will be compelling enough to secure a multi-year contract next winter. For the Mets, this is likely the first in a series of moves to address a starting rotation that is significantly depleted after the trades of Max Scherzer and Justin Verlander this summer.

The Mets have the coin to play at the top of the pitching market, and will likely do so, but this deal provides them with a short-term upside play to bolster a thin group of starters. With a rotation that is currently filled out by José Quintana, Tylor Megill, and Joey Lucchesi behind their ace, Kodai Senga, a low-cost, high-reward player was a practical move. If he performs and stays health, Severino becomes a trade option for them depending on the team’s performance. If they hold onto him, they can tag him with a qualifying offer or bring him back on a longer term deal. Either way, this move will not hurt them. Most importantly, it will not impact their ability to sign players such as Yoshinobu Yamamoto, who the Mets reportedly have interest in.

I’m sure Severino and the Mets hope that he can forget most of the summer of 2023 and instead build on the success he had in his final five starts. Among the 172 pitchers who threw at least 80 innings in 2023, Severino ranked 169th in WAR. His surface stats didn’t look any better. He set career worst marks in strikeout rate, HR/9, ERA, FIP, batting average allowed, hard-hit rate… the list goes on. As I said in his Top 50 Free Agent blurb, this wasn’t due to a concerning drop-off in rotational power. His four-seam fastball velocity (96.4 mph) was in the 88th percentile, and it even peaked as high as 97.7 mph in his second-to-last start of the season. This is a player who still has upper-90s gas in his back pocket.

As Eno Sarris has noted, Severino’s under-the-hood metrics aren’t far off from where he was during his solid 2022 season. In terms of Stuff+, he still has three above-average pitches in his heater, cutter, and slider. The former Yankee still has some compelling stuff to work with. That is good news for him, but his pitches still all performed poorly this past season. Much of that can be chalked up to poor command, but that doesn’t mean that everything is going to be alright or that he should simply continue on without making any changes. In fact, despite a 126 Stuff+ grade on his slider this past season, Severino could still stand to improve it if he wants it to be the out pitch it once was during his peak. Below is a table of his pitch velocities from 2017-23, excluding seasons where he didn’t throw more than 15 innings:

Note that Severino’s cutter isn’t included in this table because he didn’t throw it from 2017-18. During that same span, Severino used his slider almost three times as frequently as his changeup, but those marks have converged since his return from multiple injuries (including Tommy John surgery) in 2022. As a tricep/lat dominant pronator, it makes sense that Severino would throw a power changeup, but the pitch has never been better than his slider from a stuff or performance perspective. 2022 was the first time that he had more than three ticks of separation between the two pitches. But after losing two ticks on the changeup from 2022-23, the pitches converged once again. That alone isn’t necessarily the issue; rather, the three tick decrease in his slider in 2022, and the half tick decrease in 2023, was likely the most significant variable.

When looking at the run value leaderboard for sliders across the league, you’ll notice a general trend: many of these pitchers throw a hard slider. Of the top 20 pitchers by slider run value in 2023, only five of them threw the pitch with an average velocity below 85 mph. Four of those 20 throw sweepers, which are slower than the standard slider, while 10 of those 20 throw the pitch at least 87 mph.

When Severino was among the league leaders in slider run value from 2017-18, he threw the pitch at a very firm 88 mph. He lost velocity across the board from 2022-23 relative to his previous two-year peak, but the differentials vary. His four-seamer lost 1.3 mph, but his slider velo decreased by more than double that. Given the importance of breaking ball velocity, this trend isn’t ideal. The difference in speed without a change in raw movement made the pitch easier for hitters to pick up. They had more time to react, and as a result, were able to cheat on the heater more than they ever had before. It might not be possible for Severino to recover the 88 mph breaker, but even a modest uptick in velocity would be a big boost for the right-hander. Given that his fastball velocity remains high, this should be an attainable change.

After the season Severino had, the right approach is to look at what he has done in the past, evaluate what is different, and then assess what he can recover. Slider velocity is one place to start, but none of this will be possible if he can’t stay healthy – that’s his ultimate kryptonite. Before Tommy John surgery, he struggled with rotator cuff issues. After TJ, his injuries have ranged from a throwing-side lat strain, to a minor groin strain, to a throwing-side oblique strain, in that order. The latter three limited him to 191 innings in the last two seasons. His biggest question has been and will continue to be, can he deliver a starter’s workload without sustaining significant injury? Ultimately, that will be what most determines how his Mets tenure goes. That aside, the blueprint is there for Severino to improve upon his dismal 2023 season across the river in Queens.