The whole world seems to have reached the point where everybody is overrating the importance of length in point-of-attack defense. Sometimes it seems like nothing else matters. It's crazy.
You can do a lot by moving your ****ing body and cutting off driving lanes. Sure, bigger players will get off their shots easier on you than a longer player, but you can do everything else to force them into lower-value shots or into a pass. Clayton is not athletically compromised when it comes to this other stuff. He might even be athletically gifted.
I don't remember where I read this, but there has been some interesting stuff written about how some fast-and-twitchy athletes are just not as good at harnessing their fast-and-twitchiness to their observations of the offensive player they're guarding as other players (even some who are much less fast-and-twitchy). In other words, they can't connect their reading of the offensive movements with a corresponding action.
I think there are some compelling reasons to believe this kind of thing. It's certainly a lot better than what I'm hearing from Internet Bros who talk about "having all teh tools but just not caring".
I seem to recall a 6'1" Jazz guard who was a 5X all-defensive player. It can be done.