In our 9-10U rec league championship game, there were twelve 10-year olds. Four of them (among the best players on those 2 teams) were 3-year varsity starters in high school, and are playing in college, the other 8 were not (o.k., one was a girl). One of the 9-year-olds the same. So, who is right? It was not so much about "talent" as such, as it was that those 4 kids loved baseball and really worked at it. But it's easy to love something when you're good at it and have success, which is why many kids keep doing what they were doing at age 10 or 12, and not just in sports - music, chess, math, whatever. You're good to start with, you're told that if you put in the work you will stay good, and it's often true.
Honestly, how many kids do you think were not good at baseball at 10U or 12U, and then turn out great at 18U? (and I don't mean the ones who never played baseball until they were 16). Far fewer than the ones who were good at a younger age.