Well, I was never all that good at ball sports either... Mom said it was because I didn't crawl long enough :~)
I was always the slowest kid on my softball team because I had trouble running (was never very fit and I had flat feet). It was still fun until I hit high-school age and the other girls were just too far ahead of me.
I've played a few for-fun softball games since and just had to adapt my strategy. If the pitcher is lousy, which they usually are in that sort of game, I just try to get walked and after that concentrate on running. All I'm saying is that Matthew can have plenty of fun with whatever he wants, no matter what his feet are like, as long as you aren't pushing him.