Acuña was the first player to commit to the derby, and there isn’t any clear indication right now on why he won’t participate.

Ronald Acuña Jr. won't participate in the Home Run Derby, replaced Friday by Atlanta teammate and fellow All-Star Matt Olson.

Ronald Acuña Jr. won't participate in the Home Run Derby, replaced Friday by Atlanta teammate and fellow All-Star Matt Olson.

Ronald Acuña Jr. won’t participate in the Home Run Derby, replaced by Atlanta teammate and fellow All-Star Matt Olson.

The Braves' All-Star right fielder will no longer take part in the exhibition after back tightness sidelined him earlier this week.