Mitch Keller and the Pirates Tie the Knot

Brett Davis-USA TODAY Sports

It’s been a quiet winter in Pittsburgh. The Pirates lost almost no one from last year’s 76-86 team, but they didn’t add many players either. Their biggest acquisition is probably Aroldis Chapman. After that, it’s Marco Gonzales, Rowdy Tellez, Yasmani Grandal, or Martín Pérez. They’re competent major leaguers all, but hardly exciting additions. But as it turns out, the Pirates had another move to make, and it’s a welcome one:

This is both exciting and necessary, at least in my opinion. The Pirates haven’t developed many effective starting pitchers in the last, well, ever. Only one Pirates starter in the past decade has eclipsed 10 WAR with the team: Gerrit Cole with 13. After that, their success stories are Jameson Taillon, Joe Musgrove, and, well… Iván Nova is sixth on the list, and that came in 2.5 years after the Yankees traded him to Pittsburgh. As Stephen Nesbitt and Ken Rosenthal recently chronicled in The Athletic, it’s been an ugly decade for baseball in the Steel City.

Mitch Keller has already accrued the third-most starting pitching WAR in the past decade with 7.5. He’s entering his sixth big league season this year, though ups and downs early in his career mean that it’s only his fifth year of service time. The road to success has been bumpy — from 2019 through 2021, he compiled a 6.02 ERA and only racked up 170 innings of major league work. Things have gotten better since then, though. He threw 159 solid innings in 2022 and then made 32 starts in 2023, both times looking like a consistently effective starter rather than the roller coaster ride of earlier years.

Even though it didn’t quite show up in his ERA, Keller’s 2023 was a breakout season. His strikeout rate spiked from a career rate below league average to a mouth-watering 25.5%. He cut his walks by a third, going from a 9.7% mark to 6.7%. Under the hood, none of that appeared to be a fluke; he just looked better than he had in previous years. He garnered more swinging strikes. He got more called strikes. Batters chased more frequently than they had in his career before 2023 and swung at pitches in the strike zone less frequently. Across the board, his pitches simply befuddled hitters more than they used to.

How’d he do it? As Alex Eisert could tell you, he added a cutter. Well, that’s not quite right; it would be more accurate to say that he diversified his mix of sliders to improve a hard and fast one and a sweepy one. Keller used to throw a mid-80s slider around 25% of the time. In 2023, he threw a low-80s sweeper 16% of the time and an upper-80s cutter 25% of the time. In other words, he cranked up his overall cutter/slider usage by creating two distinctly different variations.

Here’s the weird part: Neither of those pitches performed particularly well, at least according to our run values. Instead, the real gain in using them was in ditching other pitches to do so. In his career before 2023, Keller had thrown his changeup and curveball around 20% of the time. More specifically, he threw those two pitches 30% of the time against lefties, and it didn’t go very well. In 2023, he cut that down to 18%. He also mothballed those pitches completely against righties, throwing them just 1.9% of the time after doing so roughly 10% of the time before 2023.

It was a classic case of addition by subtraction. Keller has long been fastball-dominant, and particularly so after breaking the pitch out into sinker and four-seam varieties in 2022. He only got himself into trouble with his secondaries, of which his slider was easily the best one. So he got smart by expanding the slider’s role, breaking it out into a cutter that gets 30% usage against lefties and a sweeper that he mostly reserves for righties.

This is a great example of working within a pitcher’s capabilities to get better results. Despite some poor home run luck, Keller looked like a solid number two starter or thereabouts after years of looking like he might not pan out. Every projection system has him down for an above-average 2024, and it’s easy to see why. In fact, Dan Szymborski projected an extension for Keller last June based on just this kind of breakout.

Dan’s projection had the extension at six years and $116 million. To be fair, that article was written in June, and Keller had a rotten second half of the season (5.59 ERA, 4.52 FIP). To be fair, that article was written in June, and Keller had a rotten second half of the season (5.59 ERA, 4.52 FIP). The actual extension was lower than ZiPS’s estimate by roughly the amount that Keller’s projection has changed (ZiPS already includes a discount from what he’d get as a free agent due to the remaining years of team control the extension buys out). The money is right within the margin of error; this deal feels reasonable for both sides from a salary perspective. Five years also feels about right for Keller to get a bite at the free agency apple if he excels on this deal.

Speaking of the open market: Before this extension, Keller was due to reach free agency after the 2025 season, when the Pirates are theoretically going to be hitting their stride. In recent years, the team has extended some key offensive contributors; Ke’Bryan Hayes is under team control through 2030 at a bargain rate and Bryan Reynolds could be a Pirate until as late as 2031. A few former top prospects have already cracked the major league roster, and more are on the way. But the team is inarguably short on pitching, and losing Keller in a year or two as the rest of the core hopefully starts to coalesce would undermine a lot of the good things about Pittsburgh’s rebuild.

To the Pirates’ credit, they’re spending money to brighten their future. Keller agreed to a one-year, $5.4 million deal to avoid arbitration this year, but his new contract will pay him $15.4 million annually. That brings our estimate of their spending up nearly $20 million from 2023, and $40 million from 2022. They’re still spending in the bottom half of the league, to be sure, and their ownership puts a pretty firm ceiling on the trajectory of their payroll, but the arc of competitiveness is headed the right way: better young core, more spending to complement it.

I’m still undecided as to whether Keller is an integral piece of that young core or just a nice ancillary option. Certainly, a contract that pays $15 million a year for a starter projected for a chunk of 3-WAR seasons is a good deal for Pittsburgh regardless of whether we call him an ace. We have him projected as the 29th-best starter in baseball this year, right on the borderline of good and great, but we project him for the 80th-best ERA, so he’s getting to a lot of his value via volume.

The next step forward in Keller’s career trajectory – or non-step, if this is as far as he goes – will be all about how he adapts to his new streamlined pitch mix. He’s always displayed a large platoon split, and that didn’t change at all in 2023; in fact, it got worse as lefties clobbered 16 homers against him. But he made up for it by ditching all those curveballs and changeups to righties, pitches he probably never should have thrown in the first place. His new sweeper is a much better fit.

It still feels like there’s something missing; maybe a splitter or a revamped changeup to give lefties at least one downward-breaking look. Fastball/slider pitchers can be effective starters, but I don’t think Keller’s raw stuff is sufficient to get away with it without at least a little tweaking somewhere else. But Keller’s contract is paying him for what he is now, and the upside of unlocking his best pitches is just that: upside. He doesn’t need to get any better to be an effective major league starter, and that’s something that’s been in vanishingly short supply in Pittsburgh of late.

There’s a chance that Paul Skenes has overtaken Keller as the best pitcher on the Pirates by midseason. There’s a chance that he’s already better, in fact. But that’s a good thing for the team, not a bad one; while they have plenty of interesting players on the roster, this is still a team with plenty of holes. This season is unlikely to be the best this team gets in this competitive cycle. Next year might be, but 2026 is a strong contender as well. Heck, 2027 and 2028 also seem like reasonable bets. Now that Keller is going to be around for all of those years, there’s no roster-driven cliff coming up that will force the Pirates to be good by a given year or have their competitive window vanish.

That’s what the best contract extensions do: give both player and team certainty. Keller is set for life financially, and he didn’t take an outrageous haircut to become so. The Pirates gave up a bit of payroll flexibility, but they gained roster stability to make up for it. It’s a good deal for everyone involved. Now if the Pirates could only add, oh, three good hitters and two good starters, they might really be cooking in 2024.





Ben is a writer at FanGraphs. He can be found on Twitter @_Ben_Clemens.

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sadtrombonemember
1 month ago

In comparison to the Reynolds deal, which seemed reasonable but not particularly important to do, this really was necessary. It’s become impossible to find playoff capable starters because they get hurt so much. You can mix and match your way to a decent left field platoon but quality starting pitchers don’t have an obvious replacement.

Skenes and Chandler and Jones offer some upside and Solometo and Harrington look like back end guys but having one guy locked in (as long as he’s healthy) is a major win.