I think many people are disappointed with Cooney's career because, while unrealistic, we expected him to be Grayson Allen before we knew who Grayson Allen was. Cooney wasn't a McD AA, but he was highly recruited by many major programs:
http://espn.go.com/college-sports/basketball/recruiting/player/_/id/67031/trevor-cooney
He was supposed to be a better shooter than Rautins, able to get to the rim like Devo, and be noticeably stronger and more athletic than both. We all saw his highlight films from AAU and high school of him driving down the lane and dunking with two hands, catching alley-oops on fast breaks, tip-slams, and swishing from 27 feet out. This is what Grayson Allen does right now for Duke.
A lot of us are disappointed because Grayson Allen was better as a freshman than Cooney is as a 5th year senior.