As some of the more rational posters have hinted at or stated, securing enough talent, keeping enough said talent and avoiding key injuries are massive. Crean has been mostly unsuccessful in all three areas, the latter two not entirely being in his control (especially the injuries). The notion of a magical coaching philosophy or in-game tactical maneuvers being able to consistently overcome inferior talent, size, athleticism, etc. is not rooted in reality. Those who believe otherwise are not objectively evaluating the entire college basketball landscape -- today and for many years in the past. There are some exceptions of course, but this is not the rule.
Crean's recruiting has been a mixed bag. Edwards, Wheeler and KD were obviously front-line SEC-caliber players. Camara was certainly capable. Crean had holdovers Claxton and Hammonds for one and two seasons respectively. Claxton's one year was basically a throwaway for Georgia, but he improved so much that he drew significant NBA interest and ultimately left for the draft. He made the right move for himself, even though his return would've likely made Georgia a 20+ win team and extremely dangerous.
Put all or most of those guys on one team for a couple of seasons and you might have something. Ultimately, none of them suited up for more than two seasons. Most had just one season, or none, together. And that's why we are where we are.
Incremental progress was being made and then key players decided "Yeah that's nice. I'm going to go join these other programs where there's IMMEDIATE guaranteed major success. They've already got this guy and that guy is going to transfer in." There is constant communication going on. Is this, too, Crean's fault? I guess in a round about way everything comes back to the coach.
My point is that today's culture makes continuity nearly impossible. If there's someone who can navigate all of this while also securing and maintaining high enough talent to successfully compete in what has become maybe the best conference in all of college basketball, then Georgia can try and find someone else.