Gray was placed on injured reserve Thursday after suffering a torn Achilles' tendon in Wednesday's practice, Ian Rapoport of NFL Network reports.
The Dolphins had listed Gray as a limited participant in the session due to a foot injury, but Rapoport's clarification of the setback provides a better explanation for why the team elected to remove the 28-year-old from the 53-man roster. While the Dolphins haven't offered a projected timeline for Gray's recovery, injuries of this nature are almost always of the season-ending variety, so it's not expected that the team will reserve one of its two designated-to-return spots for him. With Gray out of commission, rookie Mike Gesicki could be thrown into the fire as the Dolphins' top pass-catching tight end in Sunday's season opener against the Titans.