The Broncos knew they had to make a move to bolster their suddenly thin tight end corps. Veteran A.J. Derby was down with a shoulder injury and Jeff Heuerman was out with a knee injury, leaving Virgil Green as the team’s only healthy tight end on the 53-man roster. Saturday, the team promoted Austin Traylor from the practice squad and, in a surprising corresponding move, waived Derby, according to NFL sources. The Broncos acquired Derby from the Patriots late last season, giving up a 2017 fifth-round draft pick when New England had drafted him in the sixth round.