The problem with Messier is the end of his career.
Most guys just lose effectiveness and fade away - it happens, doesn't really tarnish your legacy.
Messier completely lost the plot, became caught up in his own myth, demanded to be a quasi-GM of teams toward the end of his career and wouldn't recognize his own declining skills in the process. Became a cancer and a player who made his teams worse.
The question becomes how much the last 7 years of his career take away from the first 15.
Ha, was logging on to post something very similar.
When Messier left the Rangers he was coming off 99 and 84 point seasons. Yeah he was past his prime, but still contributing well. Vancouver was a disaster both on ice (60pts was his best effort) and off. he came back to the Rangers where the GM thought the sun shone out of his butt, and he thought he'd be able lead them back to the promised land. Unfortunately, rather than see that his best was behind him and use him as a PP/burst player, the Rangers tried him as a cure-all on a horrible team and it failed miserably (although he still hit 67 pts in his first season back, which isn't horrible).
Should the last 1/3rd of his career overshadow the first 2/3rds? I say no, but it does tarnish his legacy as he faded away rather than disappearing while people still thought he had something to give.
interestingly, there were rumours during the '04 trade period that the Habs were offering a 1st rounder for him to go on a cup run but Slats said no so he could retire a blueshirt. If true, it shows that others out there still thought he could contribute under the right conditions