Chriss's lack of defensive rebounding shouldn't be poo-poohed. His 10.7% DRB rate must be historically bad for a PF... if everyone on your entire team--not just the bigs, but the guards too--had that DRB%, then you'd give up an offensive rebounding rate of 46.5% to the opposing team! Even Bender, who is correctly criticized for his mediocre rebounding, posted a 16.1DRB% this year.
Unlike shooting and turnovers, rebounding is not something that prospects tend to improve at. What you see is what you get. In Chriss's case, you're giving up multiple possessions every game, many of which will lead to easy tip-ins and free throws. I do see Chriss's appeal, but I think his lack of rebounding really limits his defensive upside, so I wouldn't pick him in the top 10.