The Indianapolis Colts left tackle exited in the first quarter of Saturday night's 27-6 preseason win over the Cleveland Browns with a right knee sprain. Third-year pro Joe Reitz took over for Castonzo, who was examined by trainers on the sideline.
Castonzo still struggles with aspects of his game. As the NFL's 32nd-ranked tackle last season, per Pro Football Focus, Castonzo led all offensive linemen with 36 blown blocks. He's not a premier tackle, but Indy can't afford to lose depth on its rebuilt line.
No starting passer was hit more than Luck during his rookie campaign, so Castonzo's status will be closely monitored.