As Ian Rapoport of NFL Network noted, McDonald was set to make $5.1 million this season. He had signed a four-year deal worth $24 million before the 2017 season, but he has been released before beginning what would have been his third year with the team.
The Dolphins will save some cash with the latest transaction, though McDonald has $3.7 million fully guaranteed, per Rapoport. They also still face $6.4 million in dead cap in 2019 and $1.9 million in dead cap for 2020, per Spotrac.
His absence will also be felt on the field, as the 28-year-old was also working with the first-team defense before the release, per Safid Deen of the Sun-Sentinel. He had been out with an undisclosed injury, per Omar Kelly of the Sun-Sentinel, and he still wasn't practicing as of Sunday.
McDonald missed two games last season with an ankle injury and was suspended the first eight games of 2017 after violating the league's substance-abuse policy.
He ranked third on the team with 86 tackles last season, adding three interceptions, but it appears the Dolphins are going to give more opportunities to Reshad Jones and Minkah Fitzpatrick at safety going forward.