Two-time All-Star catcher Matt Wieters has been ruled out for Tuesday night's game at Toronto due to a sore right forearm. Wieters has felt soreness since making a throw to second base Sunday, but says his injury is not considered serious.
The Orioles needed an extra arm after using their bullpen for 7 1-3 innings in games at Boston on Sunday and Monday.
McFarland was 0-1 with a 1.84 ERA in three starts at Triple-A. He pitched in 38 games for Baltimore last season, going 4-1 with a 4.22 ERA.
A seven-year veteran, Pearce went 1 for 7 in three games for Baltimore this season.