Kieboom is out of the lineup for Monday's game against the Pirates, Andrew Golden of The Washington Post reports.
Kieboom will take a seat for the second time in three days while the Nationals make room at third base for Ildemaro Vargas. With Kieboom turning in a modest .610 OPS in 15 games since his call-up from Triple-A Rochester in late August and with the switch-hitting Vargas offering a potential strong-side platoon option, Kieboom could see his opportunities against right-handed pitching take a hit as the season winds down.