Vrabel hired McMillan in 2021 as a defensive assistant where he primarily worked with Titans outside linebackers. In 2022, he worked as a defensive line assistant coach alongside Williams, who was named the Patriots defensive coordinator. McMillan continued to work with Titans defensive lineman in 2023.

The New England Patriots have officially hired Mike Vrabel as their head coach, Josh McDaniels as their offensive coordinator, Terrell Williams as their defensive coordinator and have kept Jeremy Springer as their special teams coordinator. Now, Vrabel is filling out the roles underneath the coordinators.