Wow! I can only go by my experience. We played baseball, football and basketball DAILY from 7am until 7pm. Rode our bikes to the playing fields. We didn't have T-ball or T-league. It started at Little League. It was a four year Little League system. There were tryouts. If you were good enough, you made the teams. I don't remember, but most did. My first year on Rexall City Drugs (took ePrescribe then), I played right field, and my main job was to drop fly balls. I complied and was 100% that year with a batting average of .024. Mind you I had made the starting lineup. The next year, I moved to left field and caught around 75% of the balls and batted around 200%. Playing all year at home, I moved to shortstop and pitcher and made the all star team. The next year almost no errors, batting average of nearly 750% and around 15 home runs.
Meanwhile, other kids chose tennis. Some practiced three hours a week, some three hours a day. Guess which ones made it to the top rankings. Same with golf, etc.
Then intermediate league for two years whee I digressed to right field, but then back to second base, where I played for four years in high school.
We have a 12-year-old in our practice (#100 -- look her up) who will be at the National Spelling Bell. Maybe we should let everyone go and use words like "yesterday."
Everyday, I do sports physicals, and I listen to their lungs while they play with their DS or Angry Birds with a BMI of 32. Should they make the team and rotate around to 3rd base?
CAVEAT: Just my example. Please don't squash me. I don't particularly think that either way these carry over to life.