I'm not as high on Joe Philbin as I am some of the others, but just because he is an offensive line coach is no reason to not hire him. Here are a few other offensive line coaches that made head coaches:
1. Andy Reid - Coached the OL at San Francisco State University, Northern Arizona, UTEP, Missouri, and in Green Bay. Never called a play until he became a head coach. Career record 126-81
2. Mike Sherman - Coached the OL at Tulane, Holy Cross, Texas A&M, and UCLA prior to coming into the NFL as a TE coach with the Packers. Spent one year as offensive coordinator for Mike Holmgren in Seattle before becoming the head coach of the Packers. Career record 57-39 with the Packers, 25-25 with Texas A&M.
3. Kirk Ferentz - Coached the OL at Iowa, Maine, Cleveland Browns, and Baltimore Ravens. Career record at Iowa as head coach is 108-87.
4. Bill Callahan - Coached the OL at Northern Arizona, Wisconsin, and Philadelphia Eagles. Coached the Raiders to the Superbowl in his first year as a head coach. 17-18 with the Raiders, 27-22 at Nebraska.