I think you ABU and I say that as a parent who's DC are not good at sport.
At my old junior school, there were a group of boys who were picked for everything. They were taken to competitions for rugby, football, tennis, cross country, cricket and swimming. They won quite a lot. A remember a good few parents going into the heads office and complaining about it, and how their DS never got picked. I never once did this.
What I would say is that in PE/ Games and after school, all were welcome, but it was the matches that they got picked for.
I know a few of these sporty DC mums and they spend a lot of time ferrying them round to sports in and out of school. Now, at 18, I know a few of them are playing at county, and national level, and a couple of them are signed up for major football clubs.
What should we have done back in junior school? Should we have quashed that talent so others, much less talented got a go? Do you think we would have good football players, rugby teams, cricketers, tennis players, olympians, if every time a school had a match, or competition, we had to be inclusive of everyone....and lose!
The way I look at it, is that every DC has a talent. Go find it, and nurture it. My DC are very talented at something that the sporty boys are not. They actually have told my DC that they think he's brilliant at it, can he show them etc. My DC have been given the opportunity to shine in their area at school. If other parents moaned that my DC always got to perform, no one else is getting a look in, then he's have less chance to develop his own skill.
Work on what your DC is talented at is my advice.