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The Twelve Days of Free Agent Relief Pitchers: Day Three, Trevor Rosenthal

On the third day of free agent relievers, Trevor Rosenthal has brought us all a blazing fastball and a wildly effective changeup. #blessed

Trevor Rosenthal by Keith Allison is licensed under CC BY SA-2.0

The Twelve Days of Free Agent Relief Pitchers: Day Three, Trevor Rosenthal

Estimated Reading Time: 4 Minutes

On the third day of this holiday, my true love is bringing the heat with the gift of Trevor Rosenthal. Thanks, true love! Let me be clear, I hope that people of all or no religions will feel welcomed in my “Twelve Days of Free Agent Relief Pitchers,” as long as they worship a fastball that averages…98 MPH!

The purpose is to rank these pitchers, but I am not positing landing spots, because marriages between particular relief pitchers and teams are more difficult to project than with position players and starting pitchers. Everyone needs relief pitching; even teams that have it wouldn’t mind having more of it, if they could come by the right deal. And teams that need it may not address it with the most obvious fit. That said, I do outline who needs relief pitching most in my first piece.

Trevor Rosenthal

Trevor Rosenthal is back, baby, and better than ever! Literally. After a disastrous 2019 return from Tommy John surgery, in which he had an infinite ERA until his fifth start of the season*, Rosenthal had the best season of his career in 2020. After performing well and saving seven games for the Royals, he was shipped to San Diego at the deadline, where he never gave up a single run for the Padres.

*It was a strikeout of Andrew Knapp that finally decreased this to a 72.00 ERA. Speaking as a Phillies fan: you’re welcome, Trevor.

Infinity to Hero

Statcast information on Baseball Savant only goes back to 2015, but it’s his best season by all of these peripheral metrics, as well. An xERA of 2.00 shows us that his real-life 1.90 ERA was well-earned. He had the third-best expected batting average (xBA) in all of baseball, after NL Rookie of the Year Devin Williams (who cleans up in a lot of these categories), and noted wizard James Karinchak.

It would be interesting to see how Rosenthal’s dominance in all of the expected stats (xSLG, xWOBA, xWOBA on contact, etc) would stack up against his 2013 season. Rosenthal broke out in his first full season with the Cardinals, the organization that drafted him, and 2013 still represents a career-best FIP (1.91) and WAR (2.2). But certainly, his 2020 strikeout rate of 41.8% has no rival elsewhere in his career. Or many other places in nature, honestly. It’s tied for fifth-best in MLB in 2020, along with another reliever who will appear later in our Twelve Days of Relief Pitchers. Stay tuned!

The Arsenal

And Trevor Rosenthal’s arsenal is every bit as impressive as its results. His fastball averages 98 MPH, for the seventh fastest in MLB, which he backs up with a slider, changeup, and the occasional sinker.

And speaking of that changeup: it led all of baseball in active spin this year. Though it was a very small sample of only 32 pitches, it had an unreal 80% Whiff rate. Speaking of things that are rarely found in nature! It seems to me that the performance of the changeup may drive the aforementioned career-high strikeout rate, given that the pitch also had an exceptional 46.2 PutAway%. (This means that 46.2% of the time that Rosenthal went with the changeup in a two-strike count, it resulted in a strikeout.)

Yes, this is from 2017, but it’s good then as now. The only shame is the incorrect @PitcherList tag.

But it didn’t appear to me that his changeup was treading new ground this year, in terms of its horizontal or vertical movement, or average spin. Granted, it’s a good changeup. But this leads me to believe that its increased effectiveness may have partly been a small-sample miracle. Despite a 2017 season with an excellent 37.6% strikeout rate, many years have hovered around 28%. That’s still a respectable mark, but not elite.

The Contract

FanGraphs’ aggregated guesses puts the 30-year-old at a two-year $13 million contract, which seems to factor in concerns that his career-best year was only a 60 game, 23.2 inning sample. The length of this track record is also what led me to rank Rosenthal after Brad Hand, despite my concerns for Hand and enthusiasm for the season Rosenthal put together.

And despite the enthusiasm I have for this tweet, which Rosenthal sent out when he joined the Padres:

C’mon. Who wouldn’t want this guy?

Ellen Adair is an actor, probably best known as Janet Bayne in “Homeland,” Bess McTeer in “The Sinner,” and Bridget Saltire in “The Slap,” but has been in a lot of other TV shows, films, and theater that the truly curious can investigate at As a human being, she is best known for her unhealthy love of baseball. It says so on her business cards. She loves baseball in general, but the Phillies are her life partner. She is the author of "Curtain Speech," from Pen & Anvil Press, and is working on bringing to life a TV series about baseball writers. Connect with her on Twitter at @ellen_adair or Instagram at @ellenadairg.

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