Every fanbase has complaints about ex-coaches. I'm sure most Blues fans were ready to move on from Berube by the time he got the ax in St. Louis, as much as they appreciated the Cup. There are a LOT of Penguin fans that don't want to see Sullivan behind the bench despite delivering 2 Cups to Pittsburgh.
Point being, you have to take what fans say about former players/coaches with a grain of salt. Another good example is Montreal fans telling us that Kovacevic sucks and will revert back to being a replacement-level defenseman any day now, despite him playing very well with the Devils this season. Players and coaches can evolve and perform better in different situations.