He was certainly a far from perfect coach on offense (anyone remember the double reverse to Billy Miller), and his defenses were 9 time out of 10 a mess. The man had faults.
The thing though is he always tried to fix those faults. He never rested on his laurels, and always put as good a product out there as possible. Given what he had at the beginning of his tenure, to what he left DA at the end, Sean should get a freaking statue.