In 1964, Detwiler was part of Bump Elliott's Big Ten Conference and Rose Bowl championship team. The Wolverines narrowly missed a National Championship in 1964, in part due to a critical fumble by Detwiler into the end zone in the team's only defeat, a 21-20 loss to Purdue. As he ran toward what appeared to be a touchdown, a Purdue defender hit Detwiler from behind, sending the ball flying into the end zone where it was recovered by Purdue. In the 1965 season, a knee injury limited Detwiler to three games. He had surgery to repair a torn anterior cruciate ligament.