What TU should have said is "height" is overrated. Mario Chalmers is a perfect example, he's only 6'1 but has a huge wingspan. He is long and because of that he is the all time leader in steals at KU. Eric Gordon was another one, they were worried about his size but he measured out at 6'9 for wingspan.
I don't think you can overrate length at all. Long athletes are key to success in basketball. Why do you think Louisville killed OU the year before last?
I actually think that OU would be ok signing Barnes and Clark and play them together with Barnes playing the 4 like a Julian Wright. That would be a crazy athletic duo with TMG, Taylor/Pledger, and Gallon in the other spots OU would be so freakin good.