I don't think D'Onofrio was the cause of Coach Golden's demise; just a mere symptom.
His inability to call a functioning D was a pretty big symptom!
Surely you realize he was implementing exactly what Coach Golden wanted. This was Coach Golden's team, philosophy and everything flowed from his decisions. He trusted that D'Onofrio would be effective with many of the things they learned together and it failed. Coach Golden wasn't following D'Onofrio. It was the other way around.
In any case, the entire thing needed and still needs to be uprooted.