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Player Review: Sean Manaea

He ran the gauntlet and came out the other side stronger for it.

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San Diego Padres v San Francisco Giants Photo by Lachlan Cunningham/Getty Images

2023 stats: 37 G (10 GS), 117.2 IP, 4.44 ERA, 3.90 FIP, 9.8 K/9, 3.2 BB/9, 3.1 K/BB, 95 ERA+

Notable: Recorded 1st career save; increased average fastball velo to career-best 93.6 mph

Sean Manaea has a no-hitter to his credit, looks vaguely like movie star Jason Momoa, and managed to pull off the rare mid-career reinvention from crafty left-handed pitcher to power lefty. The San Francisco Giants had something to do with that, obviously, and as unique as he is, Manaea’s 2023 looks vaguely like Drew Pomeranz’s 2019.

The Giants gave Manaea a 2-year deal with an opt out after the first year and at the time it felt like a bit much for a player on the fringe of being relevant. Like Drew Pomeranz, Manaea entered free agency after a big letdown season that happened to follow a remarkable one.

While his 2021 season wasn’t a career best (just a 105 ERA+) it was good enough that the Padres traded for him during one of the A’s annual fire sales. His lone season in San Diego wound up being his career worst (76 ERA+). Same thing with Pomeranz, who went 17-6 for Boston on a 137 ERA+ two years before winding up on the Giants but had his career worst (73 ERA+) just the season before which made him expendable and gettable.

Remarkably, Pomeranz’s turnaround happened before Brian Bannister and Andrew Bailey became system coaches, but the similarities remain striking. Farhan Zaidi was really the only continuity from a baseball ops standpoint — and it’s not like the Giants weren’t a successful organization from a pitcher reclamation standpoint prior to his arrival, either — but like Pomeranz, Manaea’s (brief) Giants career was a triumph of Zaidi’s process, which is actually not that mysterious: they used data to identify an aspect of his delivery that could be tweaked at Driveline’s lab that would lead to increased velocity.

Role on the 2023 team

When the deal was announced it was assumed that Manaea would join Ross Stripling at the back of the rotation and provide it with depth until Kyle Harrison was ready for promotion. As we approached the end of Spring Training, though, it became clear that the Giants had either changed plans or stuck to their original plan of using Manaea (and Stripling) less like traditional starters and more like rapid response pitchers to either chew up some innings or be late-game firemen.

The process didn’t work right away. The main thing we saw from Manaea was that increased velocity — really, truly, eye opening mph. That’s Sean Manaea? But the results were so bad in the small sample size of six weeks into the season that it prompted me to ask if Manaea and Ross Stripling were the two worst starters ever.

Sean Manaea’s slider is the 9th-worst pitch in baseball by Statcast’s Run Value rankings [-10]. Ross Stripling’s changeup [-5] is 62nd. Manaea uses his slider the most after his 4-seam fastball at 29.7%. Stripling’s changeup is his third-most used pitch (24.3%).

By basic FanGraphs Wins Above Replacement (fWAR), Stripling is the 2nd-worst pitcher in baseball (-0.6) while Manaea is 9th-worst (-0.4). If you ignore fWAR and just look at something as simple as FIP, they’re still disatrous: Stripling at 7.17 and Manaea at 6.61, the 4th- and 8th-worst values in all of MLB.

Manaea wound up having the 8th-worst slider in baseball by Statcast’s Run Value rankings (-9), but it wound up dropping from his #2 pitch to #3 by season’s end (14.9% usage). He reached 1.1 fWAR, about as valuable as Zack Greinke, Wade Miley, and Lucas Giolito. The Giants paid $12.5 million for 1 WAR, which is a big, big no-no for the efficiency hobbyists who’ve hijacked the sport.

But those mechanical adjustments stuck! The staggering failure to secure surplus value from the transaction was nearly wiped out by the results from those adjustments. It was a rough start, but Manaea wound up generating a whole lot of value. Although that 1.1 fWAR was 98th of 127 players (min. 100 IP), his 9.79 K/9 wound up being 29th in MLB (13th in NL). 44th in HR/9 (1.07), too, which really came about because he didn’t allow a homer for 11 weeks across 53.1 innings. He pitched so well that his absence from the rotation became a question for Gabe Kapler as the season unraveled.

I didn’t know very much about Manaea prior to this season except that he was a big guy who threw softly. After a season pitching for my favorite team I got to see firsthand just how tough he is. His disastrous first month as a Giant ended with an ugly line drive comebacker in Mexico City against the Padres. Watching it live it looked like an IL trip was probable and a long-term stint plausible. He started and went 5 innings just six days later.

His last four appearances of the season were starts against tricky opponents. Cleveland, despite a lackluster offense, is a tough lineup for a pitcher who walks 3 per 9. Then there was Coors Field, the Dodgers in LA and then the Padres at Oracle. The results:

24 IP
0.92 WHIP
18 K
2 BB
2 HRA
2.25 ERA (3.21 FIP)

Role on the 2024 team

He certainly pitched his way into a long-term deal the opt out now affords, but it’s probably not going to be a huge payday. Kenta Maeda just signed with the Tigers for two years and $24 million, and “value”-wise, his 1.5 fWAR didn’t make him massively better than Manaea. Certainly, Maeda and Manaea are not too comparable for reasons like the quality of pitcher, innings, etc. — lefties who can throw heat will always have suitors. Drew Pomeranz’s 4-year, $34 million deal after 2019 was a bit of a market raiser in its day and born of the idea that he could be deployed for multiple innings.

Manaea’s utility has created the potential for him to receive multi-year deals from contending teams looking for bulk/flex arms similar to how the Giants used him and from second division teams looking for traditional starters.

During those 11 weeks when Manaea didn’t give up a home run, the Giants’ pitching staff was worth 9.8 fWAR, which made them the #3 staff in MLB. I would like to have seen the version of events where all three Giants opt out candidates (Stripling, Conforto, and Manaea) had done so — would he have stayed in the Giants plans?