Why rajon rando can't shoot?

i ask this question because i heard it because he have big hands. if this is true then how come dirk nowizski, kevin garrnet, yao ming, kobe, or jordan can shoot and all of them have like 6 inches taller than him so their hands should be bigger than him yet they all are decent shooters. why he does not shoot a good as they do especially because he a PG