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Trevor Rosenthal’s track-record shows he is worth the risk

Contenders would be wise to consider the volatility of relievers, and take a risk signing Trevor Rosenthal.

National League Division Series Game 3: Los Angeles Dodgers v. San Diego Padres Photo by Kelly Gavin/MLB Photos via Getty Images

If a couple of years ago, you figured we’d be entering the 2021 Major League Baseball season ardently hoping that Trevor Rosenthal signed with your team you would likely be the only one. Following a disastrous 2019 season, it all but seemed that the once-dominant closer’s career was finished. He was still throwing as hard as ever, his fastball velocity was in the 98th percentile, but he wasn’t fooling any hitters and couldn’t find the strike zone. It was shocking going into 2020 that the Kansas City Royals were willing to take a flier on the bearded wonder.

Across 13.7 innings Rosenthal put up a 2.99 ERA and 0.7 bWARP. Most encouraging was the fact that he struck out 21 and only walked 7. That was a drastic change from 2019 when in 15.1 innings he walked 26 and only struck out 17.

It was enough for the San Diego Padres to trade for Rosenthal and install him as their closer as they marched towards the playoffs. Going from the non-pressure situation of summer baseball in Kansas City to the closer for a team chasing down a playoff spot it felt like there was a chance Rosenthal would crumble.

The exact opposite happened, Rosenthal was complete and utter nails for the Padres in every single appearance. In 23.7 innings had had an identical 2.99 DRA and 0.7 bWARP. He struck out 38 and walked eight, and ended with the same DRA- he had with Kansas City, 62. Rosenthal didn’t crumble; he met the opportunity in San Diego head-on. Somehow, someway the dude they call Big T figured it out and remerged as an arm to watch as MLB entered this offseason.

The only two noticeable differences to Rosenthal’s repertoire in 2020 compared to 2019 was that he used his changeup a lot more and put more spin on his fourseam fastball. His changeup usage increased almost 5 whole percent while his fourseam spin went from being in the 68th percentile to the 87th percentile. Still not an elite spin rate, but when your fourseamer comes in around 97-98 miles per hour you only need to be great. Mostly, the increased spin coupled with throwing the changeup more resulted in hitters not being able to sit back and tee off on his fourseamer. The extra spin made his fastball seem a tad faster while it also helped to make his changeup look like a more tantalizing offering than it actually was.

I’m not about to tell you that the 2020 Rosenthal is the same guy that will show up in 2021. Anyone who watches baseball slightly more than casually knows that relievers are notoriously volatile. One season’s solution ends up being the next season’s poison pill, but Rosenthal could come out throwing darts with pinpoint control, and he demonstrated his upside.

There’s no real way to know how relievers will fare from one year to the next, but one thing is certain: Rosenthal has earned another shot at showing the league exactly what he has up his sleeve.