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.

With Mike Vrabel having spent a season with the Cleveland Browns, there was always going to be a risk he would poach an assistant or two at his next head coaching job.

Williams reunites with coach Mike Vrabel in New England after working on Vrabel's staff for six years with the Titans.