Bradley played in just four games this season before sustaining a sprained right knee. The 2016 All-Star batted .267 with 26 homers and 87 RBIs last season.
Holt is dealing with a bout with vertigo. He told reporters that he has been experiencing "a little dizziness, a little light-headedness."
Holt is batting just .133 in 15 at-bats this season.