Gragg left Thursday's preseason matchup against the Eagles with knee and ankle injuries, Manish Mehta of the New York Daily News reports.
Gragg was a late addition in training camp to add competition for the spot that will be empty while Austin Seferian-Jenkins serves his two-game suspension. Gragg hauled in 12 passes for 150 yards and zero touchdowns for the Bills in 2015 before suffering a season-ending ACL tear in 2016, so hopefully this injury is unrelated.