"He showed little drive and motivation in practices and was outperformed by players taken much lower than him in the draft."
http://www.profootballweekly.com/2011/08/15/bills-release-2009-first-rounder-maybin
"‘I think he wants to [work hard enough]. I think he wants to,’ Gailey said [of Maybin], leaving pauses between each sentence. ‘He works at it. I’m glad you [asked that]. I don’t want anybody to think he doesn’t work at it.’”
Only a few paragraphs later, however, Gailey tacked on: “I don’t think I’ve lit very many fires [under Maybin]. We might provide a spark, but he’s got to get his own fire going.”"
http://home.buffalo.com/sports/blog/the-frustration-that-is-aaron-maybin/
The guy just didn't get it, and he didn't survive competition against undrafted free agents.... it is obvious to me that the motivation just wasn't there, and you can't be a mostly off, a little on kind of player in the NFL.