Im not saying that you are wrong.
But.... how are you coming to the conclusion that beal and ariza (or other tandems) are stronger or more physical than burks and hayward?
I assume its from watching them play since they have never competed in arm wrestling or weight lifting against one another before.
So when you watch beal and ariza you see them playing stronger and more physical than burks and hayward right? I buy that.
Now here is a question for you.
Do coaches ever affect how a player plays?
If the answer is yes then isnt there a chance that a different coach could help burks and hayward play stronger and more physical?
Since thier perceived weakness defensively doesnt come from thier size or physical limitations, then is it not possible that some of those weaknesses could be due to poor coaching?