At Wisconsin after a 1–10 season in 1990, he helped pave the way for Terrell Fletcher to run for 446 yards in 1991. In 1992, that number jumped to 492 and Brent Moss ran for 739 yards and 9 TD. By 1993, Wisconsin's offensive line paved the way for Moss' 1,637 yards and 16 TD. Fletcher also ran for 996 and 9 TD. QB Darrell Bevell was able to throw for 19 TD. In 1994, Bevell would throw 17 TD and Fletcher would run for 1,476 yards and 12 TD while Moss ran for 833 yards and 8 TD. Some of the OL that Callahan coached during this period included: Joe Panos, Joe Rudolph, Steve Stark, Mike Verstagen, and Cory Raymer.