The move comes as a bit of a surprise as McDonald had been one of the Dolphins' defensive leaders, and he seemed to embrace a role switch to become a hybrid safety-linebacker in Miami's new scheme.
McDonald, a starting Dolphins safety over the past two seasons, was due a $5 million salary in 2019. He was already guaranteed $3.6 million of that sum.
The Dolphins haven't hidden the fact that 2019 will be a rebuilding season and they intend to part with several veteran players to make room for younger players to shine. McDonald is the latest in a busy offseason of departures.
Veteran safety Reshad Jones was rumored to be on the trade block this summer, but he said Sunday that he got assurances from the Dolphins that he would remain in Miami for the 2019 season. Instead, it seems McDonald was the veteran safety the Dolphins decided to move on from before the season began.
The Dolphins are expected to start Bobby McCain at free safety and Jones at strong safety, while promising second-year defensive back Minkah Fitzpatrick is expected to play both nickel cornerback and safety.
McDonald, 28, signed with the Dolphins in 2017 after spending the first four years of his career starting for the Rams.
The Dolphins' offseason departures include quarterback Ryan Tannehill and defensive end Robert Quinn via trade, and receiver Danny Amendola, defensive end Andre Branch and guard Josh Sitton via release. More veteran departures could be coming before cutdown day.
McDonald had three interceptions and 86 tackles in 14 games (all starts) last season. He won the 2018 Good Guy Award voted upon by the South Florida media that cover the Dolphins on a regular basis.