"He does a lot for us on the field and off the field. But we're just going to have to move on," coach Bill Belichick told reporters.
It's a crushing blow for a defense that relies heavily on Mayo's ability to play in every situation. In his sixth season, Mayo was on the field for 399 of 407 defensive snaps before he was hurt. It's a loss that can't be patched over, but rookie Jamie Collins will do most of the work in Mayo's place for a defense that's allowed just 16.2 points per game.