Pittsburgh Pirates' right-hander Mitch Keller's name has come up a ton in recent trade rumors, and rightfully so. The team is bad, and Keller holds a lot of value. The way he's pitching at the moment also gives Bob Nutting a chance to get out of the remaining ~$60 million on his contract. It all makes sense.
But while Ben Cherington has made some colossal blunders during his time in Pittsburgh, trading Keller may end up being his biggest by a mile. The sort of security that Keller brings to the Pirates' rotation is not something they can easily replicate, even with their vast amount of pitching depth.
Since 2022, Keller has made 111 starts while pitching 644 1/3 innings. He owns a 4.04 ERA (106 ERA+), a 3.82 FIP, and 1.29 WHIP in those games. Keller's 21.9% K% may not jump off the page, as it's about league average. He boasts a solid 7% walk rate and a HR/9 ratio of 0.99. Keller has established himself as one of the most reliable pitchers in baseball over the last four seasons.
Not many pitchers have thrown over 640 innings since 2022; just 13 to be exact. Even fewer (11) have done that while producing an above-average ERA+ and a sub-4.00 FIP. Keller is part of a short list that includes some very talented arms, like Logan Webb, Corbin Burnes, Framber Valdez, Zack Wheeler, and Logan Gilbert. He's having yet another quality campaign this year that includes volume and strong results.
The veteran has a 3.58 ERA, 3.39 FIP, and 1.17 WHIP so far in 2025. While he may only have an 18.9% K%, his 5.7% walk rate is a career best. Another career low is his 0.72 HR/9. Keller has already made 19 starts with 113 innings of work. Both rank in the top 15 in baseball as of right now. However, of pitchers with 19+ outings and 110+ IP, only 10 have a sub-4.00 ERA and FIP.
Reliability is a hard thing to find in baseball today. With constant arm injuries and Tommy John surgeries, finding a pitcher who you can count on for at least five innings every outing (and for 30 starts a season) is hard to find. It's even harder to find one who can do that and consistently give average to above-average production. There is no replacement for what Keller brings to the Pirates.
Bubba Chandler would likely be the next man up, but he has averaged just about four innings per start at Triple-A this season. He did throw 39 1/3 innings in only seven starts after a late-season promotion to Indy late last year, but that's his best durability showing. Is Mike Burrows ready to step it up and increase his workload dramatically? Is Braxton Ashcraft ready to even toss at least five innings semi-regularly?
That's not even mentioning his affordable control. Keller is still under contract through the 2028 season and is owed just over $55.7 million. That is dirt cheap for Keller. Last offseason, Sean Manaea signed for three years at $75 million. Luis Severino also inked a three-year deal worth just under $67 million. When pitchers like Frankie Montas, Matt Boyd, and Alex Cobb are making just under what Keller is this season, then you have a tremendous bargain on your hands. Plus, do you trust the Pirates' ownership to reinvest the money saved in a Keller trade back into the organization in a meaningful way?
One could argue Keller is almost as irreplaceable as Paul Skenes. Durability, reliability, and both at a bargain price for three more years? Trading Keller would be the biggest mistake of Cherington's career in Pittsburgh. Even getting back an All-Star-caliber bat with just as much, or more control remaining, would still leave a massive void in the rotation.