Severson is one more.
Jon Merrill is an NHL caliber defenseman, but nothing special and nowhere near as good as the hype he came along with, whether it was in college or even in his first couple NHL seasons.
Mark Fayne WAS a good NHL caliber defenseman for a little while, but not for too long. He was a Conte pick in 2005, but he washed out of the league in his late 20's and probably won't return, at least not for good. He was good for a little, but it didn't last long. Pretty good pick for where he was drafted though. I believe it was the fifth round.
I was on the #FireConte train by the early 10's. I don't remember if DD was before I was or not, but I think I might have been the original member of the club. At the time I was for booting him, he had already made a few picks that would wind up being good or at least NHL caliber players, but they hadn't made their debuts in the NHL yet.