Why the Pirates trading Mitch Keller would be foolish despite depth advantage

There were plenty of trade rumors around this year’s MLB deadline surrounding Pittsburgh Pirates starting pitcher Mitch Keller. The Pirates didn’t end up moving Keller at the deadline, but it seems that didn’t completely quell rumors about the Pirates eventually trading the right-hander.

With MLB's winter just weeks away, some are already once again tossing around the idea of the Pirates trading Keller. But, contrary to popular belief, the very pitching-rich Pirates still need Mitch Keller in their starting rotation if they want a chance to compete in 2026.

Keller finished off his 2025 season with a respectable 4.19 ERA/102 ERA+, a 4.02 FIP, and 1.26 WHIP over 176.1 innings of work. His 6.8% walk rate marked the third straight season he's had a sub-7% BB%. However, his 20% strikeout rate was his lowest mark since his 2021 campaign. Keller also had a respectable 1.07 HR/9 ratio and was in the 60th percentile of barrel rate at 7.8%. Overall, it was another season of about league-average production from Keller.

But Keller’s workload, combined with his respectable results, is what makes him extremely hard to replace. Since his 2022 breakout season, Keller is one of eight pitchers who have made 120+ starts with an ERA+ average or better, along with an FIP below 4.00. The rest include Dylan Cease, Kevin Gausman, Logan Gilbert, Logan Webb, Framber Valdez, Zac Gallen, and Luis Castillo. That sort of durability is not common, especially considering he achieved it while producing decent numbers.

Mitch Keller's reliability is too valuable for the Pirates to trade.

Those who think that Keller’s league-average production means he is replaceable overlook the rarity of a league-average pitcher. This year, only 42 total pitchers had an ERA+ of 100 or better while tossing at least 150 innings. That number shrinks to only 34 hurlers when looking at the ones who made at least 30 starts this year. Keller’s lowest ERA+ over the last four seasons is 98, which only made him 2% worse than average. His fewest number of games started since 2022 is still 29.

On top of that, look at the sort of workload everyone else in the Pirates’ rotation will likely be receiving. Bubba Chandler reached 120 innings pitched for the first time in his career this past season. Johan Oviedo just came off Tommy John surgery and missed the first half of the season due to an oblique injury. He is going to be limited next year. Mike Burrows and Braxton Ashcraft both pitched 100 innings for the first time since getting drafted in 2018. Hunter Barco also only pitched 102 innings this year. We’re still looking at four or even five starting pitchers on the Pirates’ roster that can’t be relied on to deliver 150 innings in 2026. 

If the Pirates trade Keller, that means they’re relying on a handful of pitchers with limited workloads, and most have minimal experience in the major leagues, so who’s to say they could even replicate league-average results? Keller is not a flashy pitcher; he doesn’t have a significant strikeout rate, he doesn’t have overpowering stuff, and he doesn’t put up an ERA+ over 150. But what he does is give the Pirates 30+ starts and about 180 innings a season while being an average starter. He’s the definition of a rotation anchor, and unless the Pirates get back an already-proven MLB hitter in return, trading him would still be a massive mistake.