As far as physical size being a factor in the ability of one to score well, the answer is definitely "NO". As Michelle pointed out, Norm Duke is a prime example, as is Pete Weber. Yet another good example of a bowler that you will likely hear more about is Tiffany Stanbrough.....she might be small in size, but she can really crank it up from the LEFT side!
There is one lady (about age 26) who bowls in my house that is relatively small, yet she holds the women's state record for 700+ series with well over 170 of them so far. I know that between scratch leagues and my match point league, she's slapped me around with several 700's.
It's not about size.....it's more about technique, talent, and execution.