The Big Field will reveal the truth about a player. My Kid (2021) was relatively elite (for our state anyways) defensively on the 50/70 field at 2B and SS. On the 60/90 field it is clear he isn't quick enough to be more than a 3B/1B. He is determined to close that quickness gap, we'll see. The lack of speed is a detriment for him in the outfield, too, in ways that weren't revealed on the smaller field.
On the plus side we had heard for years about how tough of an adjustment BBCOR was and that kids will struggle to hit the ball out of the infield when they first start swinging BBCOR. That was never an issue for my son. Even at age 13 he was driving the ball with a BBCOR bat....