You pose an interesting question about Gassoff in your original post. The problem in any discussion about Gassoff is that although there is no doubt that he was great and there are lots of stories but very little footage. He is much like Battleship Kelly or Jack Carlson
In regards to the "Missing Link" to me there is no doubt that he could have been an all time great. In the WHL he put a severe pounding on Tony Twist
. In his short NHL career he had a great toe to toe bout with Probert 2 great fights with Kocur in one of them he stood in there and took a few flush right hand bombs from Kocur and didnt quit on the fight or go down.
He also dropped the very tough Randy McKay
I don't have Link's win loss percentage in the NHL in front of me but on first glance I def agree with your premise. His career in the NHL was cut far too short due to his own antics but he continued to be a force in the Minor Pro leagues and the Quebec Semi Pro league for sure