The Royals have moved right-hander Brad Keller from the rotation to the bullpen, manager Mike Matheny announced to reporters (link via Lynn Worthy of the Kansas City Star). For now, Matheny indicated the plan is merely to “take a look” at Keller in this role, suggesting the organization hasn’t necessarily giving up on him as a starter entirely.
Keller’s shift to the ’pen is a reminder of how quickly things can change in baseball. Just a month ago, he looked the part of an appealing trade chip for the Royals, having pitched to a 3.96 ERA through his first 17 starts. Keller’s 16.4% strikeout rate in that time was well south of the league average, but he also boasted better-than-average walk and ground-ball rates (7.8% and 51.6%, respectively). He’d done a fine job managing hard contact and, while obviously not an overpowering pitcher, looked well on his way to another season as a solid back-of-the-rotation innings eater.
In five starts since that time, however, Keller has been rocked for 25 runs (24 earned) through just 24 2/3 innings of work. He’s twice surrendered eight runs in a start and yielded five home runs in that time (after allowing just four in his prior 43 innings of work). Keller has also walked an uncharacteristic 12.3% of his opponents during this stretch, and after allowing an 88.5 mph average exit velocity and 38.8% hard-hit rate through his first 17 starts, has yielded a 92.1 mph average exit velo and 50% hard-hit rate during this recent slump.
It’s a jarring stretch, one that mirrors many of the struggles the 27-year-old endured in a down 2021 year that, until recently, looked like an aberration. Keller was a steady member of the Kansas City staff from 2018-20 before slipping in ’21 and posting an unsightly 5.39 ERA in 133 2/3 frames (26 starts). The primary factors behind his struggles were spikes in both his walk rate and home-run rate, as has been the case over the past month. Even with those 2021 struggles and this recent stretch of five dismal outings, Keller still carries a career 4.19 ERA with well above-average ground-ball tendencies.
As is always the case, there’s a certain level of intrigue when taking a starter and dropping him into a relief role. Pitchers typically throw harder when they know they’re working in short stints and can thus throw at a higher intensity without needing to worry about saving some gas for second and third trips through the batting order. Keller’s slider has long graded out as a plus pitch, and we know he can rack up grounders. If a few extra ticks of velocity can improve the results on his sinker or generate some extra whiffs with his four-seamer (which already has above-average spin), it’s possible the bullpen version of Keller could turn some heads.
On the other side of the coin, of course, continued struggles in his new role could muddy the waters for Keller and his outlook with the Royals. He’s already in his fifth season with Kansas City, and the former Rule 5 draft pick — one of the best Rule 5 selections in recent memory, to the Royals’ credit — is only under team control through the 2023 season. He’ll be due a raise on this year’s $4.825MM salary in his final trip through arbitration this offseason, and although his struggles will limit the magnitude of that raise, he could still pull in something north of $6MM.
The Royals may tender Keller a contract regardless, considering that a reasonable price to pay for a pitcher with his track record — 2022 struggles notwithstanding. Still, a nice finish to the season — whether pitching well enough out of the ’pen to win back a rotation spot or simply shining as a reliever down the stretch — would solidify the ground on which he’s standing. The Royals did discuss Keller with other teams prior to the trade deadline, so it’s likely that those interested parties will also be keeping tabs on how he performs in a new role.
With Keller stepping to the side, the Royals’ rotation will have some fluidity. Zack Greinke will remain in place as a veteran workhorse, followed by right-hander Brady Singer, who appears in the midst of a breakout. Lefties Daniel Lynch and Kris Bubic have pedestrian numbers overall but have both been quite sharp in their past eight starts. Any of Jonathan Heasley, Jackson Kowar, Drew Parrish or Max Castillo could be options to step into Keller’s rotation spot down the stretch.
Those numbers for Keller have also been fairly consistent year-over-year, with his strikeout rate always falling between 16.3% and 19.6%, his walk rate between 7.8% and 10.4%, with his grounder rate between 47.8% and 54.4%. But as a ground ball pitcher, the one thing that’s not consistent is BABIP, or batting average on balls in play. Strikeout pitchers naturally have more control of their outcomes as they aren’t reliant on batted balls finding gloves and being fielded cleanly. A pitcher like Keller can be helped or harmed by randomness in this regard. For instance, in 2020, Keller’s BABIP dropped to .233, about 50 points below his previous seasons. That led to a career-best 2.47 ERA that year. However, the wheel of fortune spun him round the other way in 2021, as his BABIP shot up to .347 and took his ERA to 5.39.