The Dolphins believe that linebacker Raekwon McMillan has torn the ACL in his right knee, Armando Salguero of The Miami Herald tweets. MRI results on Friday morning confirmed the injury. 
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The Dolphins had big hopes for McMillan after he topped 100 tackles in each of his last two seasons. After Koa Misi landed on IR, Miami planned to use McMillan as its starting middle linebacker with Lawrence Timmons and Kiko Alonso at the outside spots.
Of course, the full-on ACL tear automatically rules out McMillan for the entire season. If that’s the case, the Dolphins can be expected to look into signing a free agent linebacker or two.
Notable inside linebackers on the market include Perry Riley, Rey Maualuga, and Daryl Washington. Meanwhile, Arthur Brown and O’Brien Schofield are among the 4-3 outside linebackers without teams. If the Dolphins aren’t crazy about the current crop of options, they could wait until the 53-man deadline approaches to see who else may come available.