Pittsburgh barely lost last year and IMO I wouldnt want to be the team in the way of Sidney Crosby if he's pissed. Pittsburgh is a dynasty in the making, Detroit is kind of like the '83 Islanders, in other words Pittsburgh had to lose to someone first before winning a few
Joe Mullen spent 8 years in the St. Louis organization, played as many games for St. Louis as he did for Calgary or Pittsburgh, and put up multiple 40-goal seasons for the Blues. He doesn't fit this at all. Aside from his one huge year in Calgary, the most productive years of his career were as a St. Louis Blue.
Mullen with St. Louis isn't much different than Dale Hunter with Quebec. Just because they played forever after leaving, doesn't mean that they weren't major players for that franchise and it shouldn't be 'weird' to see the player in that jersey.