Sisco was hurt during the seventh inning of the Orioles' game against the Angels on Tuesday.
Alvarez and Sisco pursued Ian Kinsler's foul popup near the Angels' dugout. Alvarez reached out his glove and caught the ball, but Sisco slid into Alvarez's outstretched elbow.
Sisco went down motionless, and Mike Trout immediately waved for the Orioles' training staff from the on-deck circle while the Angels' staff assisted.
Sisco stayed down for several moments but eventually sat up and left the field to applause. He was replaced by Caleb Joseph.
Sisco was born and raised in nearby Corona, California.