Thomas then was hired as GM of the San Francisco 49ers in 1977 by new owner Eddie DeBartolo at the recommendation of Al Davis and immediately fired head coach Monte Clark. The 49ers went 7-23 in Thomas' two seasons with the franchise, and his biggest trade, a series of 5 high draft picks for O.J. Simpson, was a colossal bust, as Simpson proved to be washed up. Thomas also fired two more head coaches, Ken Meyer and Pete McCulley, and Thomas' third hire, Fred O'Connor, was fired along with Thomas at the end of the 1978 season. Fortunately for the 49ers, the new GM/head coach, Bill Walsh, targeted a quarterback in the third round named Joe Montana, and the two of them restored San Francisco's franchise from the lows under Thomas.