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.