Despite playing in less than 50 total games last season, the Nationals showed confidence in Kieboom by challenging him with an initial assignment to High-A Potomac to start the year. Just 20-years-old for the entirety of the 2018 regular season, he’s already hitting third and manning shortstop for the P-Nats. He added muscle this off-season, now looking every bit of his athletic 6’2’’ and 200-pound listing. Kieboom’s batspeed has improved because of the strength gains, and he’s showing more consistent loft power in game situations. His swing-path is lengthier than when I saw him as an amateur, but he’s doing more damage at the plate as well. Kieboom understands how to work himself into fastball counts, which is a good sign for a hitter who shows more present swing-and-miss against off-speed stuff. Defensively, I came away impressed with his improvements at shortstop: last year, I saw a player likely to move off the position, though he now looks to have at least some chance to stick at short. Kieboom will never be truly plus defender, but both his range and overall actions have taken steps forward since 2017.
One of the better infield prospects in the low-minors, Kieboom’s offensive profile will be extremely valuable if he can remain up the middle on defense. The ceiling is an offensive-minded shortstop with a above-average hit and power tools on top of a passable glove. Likely more of an everyday guy if he moves to the hot corner, the bat still could be enough to get regular playing time at third base. Washington has had great success developing left-side infielders like Anthony Rendon and Trea Turner, and Kieboom has the tools and makeup to be the next name on that list.