My best friend lives in Southlake. His daughter is on the girls varsity swim team. Great program there in Carroll.
It's a well oiled machine, and it starts in second grade. Their middle school teams rarely lose a game, and stay very competitive during high school.
I never saw it before moving to North Texas 20 years ago, but there are communities where parents hold their children back a year for athletic reasons.
I never did it with my sons, but I can see the rationale for it. My boys are late bloomers, as was I. I didn't have my growth spurt until my sophomore year, and I saw the difference while competing at the JV level.
My youngest son is a freshman now, and has grown 6 inches over the past year, to just under 6 feet high. Playing against those Southlake kids who averaged several inches and 20-30 pounds more than their opponents, was a joke. My sons learned some valuable life lessons from that.
The Southlake community has bought into it, so be it. There's a lot of money there, and they know how to spread it around.