My one daughter started soccer at 4, and had similar results to shmeguins kid. Wouldn't leave my side, just stood out there, etc. She started to break out a bit at 5, and really took off at 6. Now at 9, she is on the U10 travel squad and doing really well.
Meanwhile, my other daughter started off great at 4, was that kid that was advanced, and now at 7, hates the sport and wants to focus on dance/gymnastics.
Moral of the story, every kid is different and have different reactions, grow at different rates, and have different interests.
We always told our kids, we aren't going to force them to do anything: sports, music, art, dance, etc, as long as they do something to keep active. It's their choice.