"A.J. is a young tight end who can help us immediately," general manager John Elway said, via the team's official website. "He has tremendous upside and will fit in well on our team."
A sixth-round pick in the 2015 NFL Draft, Derby missed his rookie season with a knee injury. The former college quarterback opened eyes in training camp this past summer, though, hauling in 15 passes for 189 yards and a touchdown in four preseason games.
When Belichick noted in August that his tight-end group was the deepest he has ever seen in New England, he singled out Derby as a key component.