Despite playing in less than 50 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, Kieboom has hit his way to Double-A and was named to the Futures Game.
He has added noticeable muscle entering this year and is holding up better as the season goes on, now looking every bit of his athletic 6’2’’ and 200-pound listing. Kieboom’s bat speed 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 a truly plus defender, but both his range and overall actions have taken steps forward since 2017.
One of the better infield prospects in the minors, Kieboom is a good blend of floor and ceiling. His offensive profile will be much more valuable at shortstop, and he could be a star if he can remain at the position. He’s still a solid everyday guy if he moves to the hot corner. 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.