Gillmore is dealing with a potentially serious knee injury, Jeff Zrebiec of The Baltimore Sun reports.
Baltimore entered the offseason with impressive depth at tight end, but the team lost Dennis Pitta (hip) and Darren Waller (suspension) before training camp, leaving Gillmore to compete with Ben Watson, Maxx Williams (knee) and Nick Boyle for snaps. Gillmore has struggled to stay healthy since serving as Baltimore's top tight end for much of the 2015 season, playing in only seven of the team's last 20 games. He may be in danger of a long-term absence, and at the very least, he'll fall behind in the position battle. Despite the fact that he's 36 and missed all of last season with a torn Achilles, Watson is the early favorite for the Week 1 starting gig.