I agree completely but Marion's personality unraveling didn't occur in a vaccuum. Various Sports guys (especially the fantasy/stats people) started calling him the most underrated player in the game and then came all the questions about whether he was valued properly.
The first time I heard it was on the NBA channel and the host, during a post game interview, specifically asked him if he felt disrespected - Marion mumbled no. But that opened the floodgates and for the next several months any time anyone put a mic in front of him, that question would be asked. Shawn didn't handle it well, neither did Dice when he went through almost the same thing with us several years earlier. Maybe a more astute organization figures out how to get ahead of that problem but ours never did.
And like HH said, Marion had the superior career, peak Amare was the superior player. In both cases, it's not all that close IMO but Shawn had good health and Stat had one injury after the other.