Jim Harbaugh's coaching staff at Michigan appears to have undergone a significant change, as offensive coordinator Tim Drevno has decided to step down from his role, Bruce Feldman of Sports Illustrated reports.

The move comes as somewhat of a surprise considering Drevno's history of working with Harbaugh. Prior to joining his staff at Michigan in 2015, Drevno served as Harbaugh's offensive line coach with the San Francisco 49ers from 2011-13, as well as both tight ends coach (2007-08) and offensive line coach (2009-10) on his staff at Stanford.

A replacement for the 48-year-old has yet to be named, although recently hired offensive analyst Ed Warinner is expected to take over duties as offensive line coach for the Wolverines, according to Feldman.