@Linkat,
Huh.
I was recently watching a soccer game before my daughter's, boys younger than her. One of them is the younger brother of a classmate of hers who I know is an amazing athlete. Turns out that the younger brother is also amazing. I watched about 10 minutes and in that time he scored four goals, pretty much effortlessly, and nobody seemed surprised. I don't know what the final score was but from reactions it looked like he'd already scored many, many goals.
That rubbed me a bit wrong -- he should be in another league, or he should just dial things down a bit. (Honestly, re: "effortlessly," I think he probably already had dialed things down a bit.)
If a single player is that dominant then nobody else really gets the soccer experience. And at age 11, I think that's still important. (Amazingboy's teammates looked bored and listless, even though they were apparently winning by a vast amount. They didn't do much but pass the ball to him, or kind of kick it in a general way and wait for him to go get it, which he was able to do most of the time.)
That's more my concern than the opposing players being discouraged.
I've definitely seen that on sozlet's teams too -- she's never played with a super-dominant player, but there is always a best player of course and I've noticed that in every sport, she and her teammates step up and play better when the star isn't there.
But not sure where to draw the line or how to enforce it.