I admit I'm not as experienced as many others around here, but my understanding is that in DIII, a guy with a 95 rating in anything is probably going to be very successful at that thing, even if his other ratings are bad. I actually had a guard with a 97 defensive rating when I took over my current team, and that was my best season of HD; in fact, the only guy to graduate after that season was the 97 defensive guy (who didn't even start, but I suspect shut down opposing guards when he came into the game), and lo and behold, my team did worse the next year.
So I wouldn't be too deterred by his poor ATH and speed ratings. Would it be good if he had 80 in both? Sure, and in fact it would probably make him one of the best defensive DIII players ever. But with 95 defense, I suspect opponents will still have a lot of trouble with him, or at least you guys you match him up against won't score nearly as much as they should.