Suppose you have two groups of people: a thousand 15 year olds from various track teams (Group A), and a thousand 15 year olds who've never been on a track team (Group B). Everyone in both groups are optimally trained for their best event for the next 5 years. Which group would have the faster PRs, group A or group B?
One of my friends says that Group B would win because the track team is mainly composed of people who're just joining so that they could be with their friends, rejects who couldn't hack it in other sports, and people who're joining because it doesn't look that hard and because it makes their college apps look good (and/or makes their parents happy). But another one of my friends says that Group A would win since the track team is composed of already fit guys who want to maintain their shape for football, soccer, and/or basketball.
I'm an adult-onset runner who's never been on a track team, so who's right?