"It is an honor and a privilege to join the University of MI football family under Coach Harbaugh, one of the most successful head coaches in all of football", Gattis said in Michigan's release.
Gattis spent one season in Tuscaloosa as Nick Saban's co-offensive coordinator and wide receivers coach.
Gattis will inherit a number of offensive weapons at MI, including quarterback Shea Patterson and wide receivers Donovan Peoples-Jones, Tarik Black and Nico Collins.
Michigan's offense didn't have an official coordinator in 2018. He was set to join forces with Maryland's new head coach Mike Locksley, with whom he shared the role of offensive coordinator at Alabama in 2018. McElwain is now the head coach at Central Michigan. And that's not counting Steve Sarkisian, who was the Tide's offensive coordinator for the 2017 national championship game before moving to be the offensive coordinator for the Atlanta Falcons.
The Wolverines were just outside the top 20 in scoring offense in 2018 and averaged 6.1 yards per play.
With Gattis on staff, the Crimson Tide posted the best offensive season in program history 522 yards per game and 45.6 points per game. He stayed with the team through its run in the College Football Playoff despite accepting the head coaching job at Maryland in December.
The Michigan offense bookended the season with poor performances, however. With Shea Patterson back for his senior season in 2019, that ratio could be different next season.
Harbaugh's staff has undergone some significant changes this offseason after he said following Michigan's loss to Florida in the Peach Bowl that he expected very few.