I can't give you stats but I since I have got my enthusiasm up to a 9-10 every game I am dominating my opponents. In two games:
Against rivals on their home court TIE won by 8 with about a 7 enthusiasm.
Against #2(at the time) team on their home court TV game TIE and won by 13 with about 9 enthusiasm.
It is very beneficial. Once you get it up keep TIE and its like playing CT every time. Great advantage over teams that have no idea about it.