Mullins is out of the lineup for Sunday's game against the Red Sox, Roch Kubatko of MASN Sports reports.
Manager Brandon Hyde has occasionally shielded Mullins from left-handed starting pitchers this season, so it's not overly surprising that the 24-year-old will head to the bench with David Price on the bump for Boston. Joey Rickard will start in center field in Mullins' stead and hit second.