People seem to forget that, Martz was the QB Coach Vermeil hired him as OC which did aid in bringing in Trent Green too although Green being from St. Louis did not hurt.
As to your original inquiry might be never. Before Offensive Coordinators the Offensive Line Coaches pretty much ran the offense so Chuck Knox was the OL Coach in Detroit before he was hired by the Rams in 1973. Hampton Pool handled the Teams offense & defense for the Rams when they won the NFL Championship in 1951 and took over Joe Stydahar after their season opening loss in 1952. So Hampton Pool would be the most successful offensive coach to oversee the Rams if you exclude Mike Martz.
George Allen was a defensive coach, Tommy Prothro came from college, then Knox was the Offensive Line Coach, followed by Allen for two preseason games then Ray Malavasi and technically Malavasi was the offensive coordinator under George Allen, but was notorious as a DC which he was under Knox. John Robinson came from USC, then Knox again followed by Rich Brooks then Dick Vermeil. Scott Linehan was an OC from the Vikings, but he was a disaster.
