He needs to be able to stay healthy like he did last year, if he's getting nagged by injuries all year, he's not going to be nearly as effective.
I'm sure he'll be a love/hate kind of guy, you'll love him one game and call him out the next. Consistency is what the good and great receivers have, so it's hard for me to think highly of Desean when he takes games off. From a statistical view, he had a pretty good past season, but he still had about 5 games where he only caught a few passes for minimal yardage.