Turgeon, IMO, could have been better and done more, but until he went to St. Louis, his teams were not exactly stacked.
Buffalo- That 1990 team with Housley, Andreychuk, and Puppa was third overall- and his Sabre teams were not awful- but they were stuck in the Adams Division in an era and format where Boston and Montreal always won. You put his teams in the Patrick Division, and maybe things are different. Turgeon might have been better suited if he wasn't in the small rinks of that division. It didn't help to play in a division during a stretch were the Habs and Bruins loomed over everyone else.
Islanders- They were never, ever known for goalie stability. The one year they had it, they let him go to the Rangers and made the Hextall trade a year later.
Montreal- He, Recchi, Damphousse, Koivu- not a bad armada. I still wonder what the Habs were thinking when they traded him for Corson.
St. Louis- Location, location, location. This was smack in the middle of the 'Detroit, Dallas, Colorado, and everybody else' Western Conference.
You could make a case Turgeon had a lot of bad timing and luck.