I am not saying its just Big Hands = Bad Shooting. No doubt there have been players with large hands who have been decent shooters, even great shooters. No doubt there have been players who can palm the ball very easily and still hit jumpshots (see Jordan, Michael).
But I support the idea that Big Hands can lead to Bad Shooting because large hands and being able to the palm the ball easily, like right off the catch or dribble, gives the player a unique advantage that a majority of players, particularly at young ages, do not have. This is where bad habits - or just habits - are formed.
Maybe it is more palming and the bad habits formed by this than it is large hands in general - and of course you need large hands to palm the ball. But I agree with Reggie that Rondo's hand size does not HELP his jumpshot percentage.
Now, this I can see a little bit. Although, I actually think it would be more his freakish athleticism. He didn't have to learn to be a good shooter when he was younger, because he could just get to the rim whenever he wanted.
I don't think it is a coincidence that there are so many great shooters who are not elite athletes. That is because they were forced to dedicate themselves to that shot, in order to be better than the guys who had more natural gifts.
Guys like Ray, who have the athleticism and the shot are incredibly rare. It is tough to get a 15 year old to put up 500 shots a day and work on his form, when he is already dominating games against Seniors, even without a good outside shot.