I'm in the minority here, but I do buy the "large hands" theory. It's harder to get that ball resting perfectly on your finger tips when you have large hands. Players with very big hands can overcome that and become good shooters, but they rarely do it with that textbook Ray Allen or Steve Nash form.
Think Magic Johnson for a good example of this. He became a decent shooter over his career, but his form was never pretty.
OK, I am confused. If they have bad form, then why is it their hands that are causing the problem?
It is like blaming your golf clubs for your slice, when you are pulling away from the ball (or something like that). Sure, maybe you can get a new, fancier, golf club that will help to straighten it out a little, but you don't really fix things unless you fix your form.
I've never played golf, but I don't think that's a good analogy. You can change your golf clubs, but you can't change the size of your hands.
Regardless of the analogy, I am still having trouble grasping how you are arguing that big hands would prevent shooters from having good form.
Now, I can see an argument where a player could have great form, but does not shoot as well as someone like Ray Allen, because of his hands. Then it makes sense. But when someone has bad, or inconsistent form, that is a MAJOR confounding variable for determining whether the size of their hands are a problem.
Unfortunately, I haven't done a major, comprehensive scientifically based research study on the relationship between shooting form, accuracy, and hand size.
I guess all I'm saying is that having large hands seems to make it harder to have good form. This is not based in research, just on what I know about shooting a basketball, and being taught to keep the ball on your finger tips for release. I have average sized hands so the ball fits nicely in my hands for keeping the ball on the finger tips for release while keeping a nice L shape with my elbows.
Guys with bigger hands seem to need to adjust that technique a little so the ball doesn't slip out of their hands. Often times you'll see guys raise the ball higher over their head than out in front of them or accept some palming and employ more of a slingshot technique.
I'm not saying players with bigger hands can't learn to shoot, just that, generally, some adjustments to the text book form that I learned as a middle schooler can be helpful if your hands outgrow the ball.