The OP said opposing coaches. I read that as present tense. Those still coaching today, Bill Snyder would have to be at the top. With a year or two exception in there, he does the most with the least of any coach coaching today. Bob Stoops took over an underperforming OU team and almost overnight made them winners. Even though June Jones isn't at Hawaii anymore, he is still coaching which is why he made my list. The year before he took over at Hawaii, they lost every game. June Jones put Hawaii football on the map.