Mike Hull, an undrafted linebacker heading into his third season with the Dolphins, is listed behind McMillan on the depth chart but has just one career start, which came last season.
The Dolphins were waiting word Friday morning on the extent of the knee injury sustained by rookie linebacker Raekwon McMillan, which unfortunately became the biggest story of the preseason opener against the Atlanta Falcons.
This won't quite register on the same scale as Ryan Tannehill's knee trouble has, but the Miami Dolphins lost one of their top offseason investments during their first preseason game Thursday night.
McMillan was taken in the second round with the 54th overall pick in the April draft after making 275 tackles in three seasons at Ohio State.
McMillan suffered the injury on his first play of the game on punt coverage. The Dolphins may have to dip into free agency or test the trade market if the reports of his injury are true.
Linebacker Koa Misi's season ended two days before the start of training camp when he was placed on injured reserve because of a lingering neck injury. Head Coach Adam Gase said after the game that the plan had been for McMillan to play the entire first half. Alonso led the Dolphins with 69 tackles this past season.