Kieboom (elbow) was placed on the 60-day injured list Monday, Matt Weyrich of NBC Sports Washington reports.
Kieboom was diagnosed with a flexor mass strain in his right forearm this weekend, and the issue will force him to miss the first two months of the regular season. Maikel Franco is now the favorite to begin the year as Washington's primary third baseman, but Kieboom will be in the mix for the role once he's cleared to return.