Carter Kieboom

The Nationals planned on having Kieboom compete for the starting job at third base, but he was first diagnosed with a flexor mass strain before learning he also had a sprained UCL. After attempting to rehab, Kieboom had Tommy John surgery in May, with an expected recovery in advance of spring training. With the late season emergence of Joey Meneses and the acquisition of Jeimer Candelario, Kieboom's clearest path to playing time could be designated hitter, which may not be a bad thing, at least early. Whether he earns the job is the question. Kieboom's MLB OPS is just .589, and he's been off for a year. He's worth tracking in the spring, but pre-injury, Kieboom demonstrated limited ability to handle major league pitching.

Kieboom's prospect status continues to fade. The 24-year-old was once viewed as Anthony Rendon's heir apparent at the hot corner for Washington, but over the last three seasons he's stumbled to a .589 OPS over 414 plate appearances in the majors with a 26.8 percent strikeout rate. Kieboom's struggles as a hitter have followed him into the field and also accompanied him down to Triple-A Rochester in 2021, and the Nationals have cycled through a number of veteran stopgaps while waiting for things to finally click for the 2016 first-round pick. That wait will be even longer after Kieboom was diagnosed with a sprained UCL in his elbow and a flexor mass strain in his forearm this spring, putting the possibility of Tommy John surgery that would likely cost him the entire campaign on the table. Even if he does avoid surgery and is able to get back on the field over the summer, Kieboom has a lot to prove before he'll be able to take over at third base on the big-league roster.

Kieboom won't turn 24 until September and has appeared in just 44 games at the highest level, so there's still plenty of time for him to deliver on his fairly considerable prospect promise. Through parts of two seasons, though, he hasn't come close to demonstrating that he'll eventually get there. In 33 games last year, he managed zero homers or steals while hitting just .202/.344/.212, giving him a career .181/.309/.232 line through 165 plate appearances. At least he's walked at a 12.7% clip, but a 29.7 K% and .051 ISO are both very disappointing marks for a player expected to hit for both average and power. He has little left to prove in the minors, having posted a 123 wRC+ at Triple-A in 2019, and the Nationals say he'll have the inside track on the starting job at the hot corner this year, so he's still a fine upside play for those wanting to bet on talent, but the floor here is clearly quite low.

It was a three-part season for Kieboom, who peaked (.379/.506/.636) in 18 games at Triple-A before getting promoted and falling flat (17 wRC+) in 11 big-league games. He was then optioned back to the Pacific Coast League, and from there he performed as expected, hitting .289/.391/.458 with a 19.7 K% in his final 90 games. Kieboom was 23% better than the average PCL hitter despite being the youngest qualified hitter on the circuit. Despite significant struggles in his brief MLB stint, his batted-ball profile at Triple-A was encouraging (22.4 LD%, 39.8 Pull%), so it still seems likely that Kieboom will acquit himself well with the bat over the long run. That said, he may not be amazing in any one fantasy category and certainly won't contribute much with his legs. The Nationals brought back Asdrubal Cabrera and signed Starlin Castro, so Kieboom may have to bide his time in the minors for a little while yet.

Kieboom was an elite hitter at Low-A and High-A, and while he remains a good prospect, his stock has leveled off since a promotion to Double-A. He struggled to hit for power in the Eastern League, notching a .133 ISO in 62 games. That trend continued in the Arizona Fall League, where he hit .295/.427/.372 -- leading all hitters in walks (17) while tallying just three extra-base hits in 78 at-bats. He won't need to be a middle-of-the-order bat to play every day, but the expectation a year ago was that he would be at least a 20-homer threat in the majors. It now seems a little less likely that Kieboom hits for impactful power while also hitting around .280. Perhaps he ends up hitting .265 with 25 homers, which is still valuable production from an infielder. If Anthony Rendon leaves in free agency after the 2019 season, Kieboom will serve as his long-term replacement at third base. That said, if Kieboom looks ready this summer, he may debut at the keystone.

In an injury shortened campaign, Kieboom still impressed enough in his first year in a full season league to generate Troy Tulowitzki comps. Prior to a mid May hamstring injury that cost him 10 weeks, he slashed .333/.398/.586 with six home runs and a 25:10 K:BB in 123 plate appearances. While Kieboom was quite a bit worse (.755 OPS) after returning to Hagerstown in mid August, he still got on base a ton (.402 OBP, 18 walks in 19 games), and looks more than ready for an assignment to High-A. Thanks to impressive bat speed and a very advanced approach, the 6-foot-2 shortstop has the foundation to hit for average and for power, potentially flirting with some .300/.400/.500 seasons. He is a below-average runner, so his bat will have to provide all of his fantasy value. His defense at shortstop is passable, but not good enough to displace a quality option, so it’s possible his future home is second base or third base.

The 28th overall pick in the 2016 draft, Kieboom was seen as a polished high school shortstop without a true standout tool, but average to above average ability almost across the board. That scouting report didn't exactly bear fruit in his professional debut, as he hit just .244 with 43 strikeouts in 36 games in the Gulf Coast League, but plenty of prospects have gone on to excellent careers after struggling as 18-year-olds in their debuts. Long term he may outgrow shortstop and move to third base, but he has the arm for the position, and his ultimate fantasy value will depend on how his power stroke develops as he likely won't offer much on the basepaths. He's not an elite dynasty asset by any means, but assuming he bounces back in 2017, Kieboom figures to provide the Nationals with solid production with both his glove and his bat beginning in the early 2020s.