Gray suffered the injury -- a non-contact injury during 1-on-1 drills -- during Wednesday's practice and was placed on injured reserve Thursday. Tight end Gavin Escobar was re-signed to take his roster spot.
"There were a lot of us that went to go see him when we got back," said Dolphins coach Adam Gase. "It was tough to see that."
This means it's Mike Gesicki time in Miami. The rookie second-round pick out of Penn State showed signs of brilliance during training camp and was expected to play a key role in the red zone, on third down and in other specialty situations.
Now Gesicki will be expected to take a starter-like role along with A.J. Derby in Miami's offense. Tight end Durham Smythe, a rookie fourth-round pick out of Notre Dame, will also see an increased role as a blocker.
Gray was the Dolphins' most complete tight end as a receiver and blocker. Escobar spent the offseason with the Dolphins before being let go on cut-down day.