I'm nitpicking here - I've really come around on him, too, and I hope we get him - but my take from that article wasn't that he had only played basketball for 5 years, but more that he hasn't played SERIOUS basketball for more than 5 years. I think he has played at what you might call a "normal" jr high and high school level for a while, but only started playing serious AAU ball in the summer before his Sr year of high school. (And because of this, he wasn't highly recruited out of high school - he just didn't have much exposure)
But really I think your point still stands - he could likely greatly benefit from working with a top level program, facility, coaching staff, and even improve just from consistently facing and adapting to top level competition.