I've seen a big increase from second-year 12u to first-year 14U.
In 12U last year, we had two girls who could clear a 200-foot fence, although neither did it in a game. This year, we have five girls that can clear 200, and two have done it. (It's a different team, but very comparable talent.) I saw 5 HR in a tournament Saturday, and that's just the games I was watching. I never saw that many last year n 12U.
Also, my daughter's power has increased very significantly in the last 9 months, largely b/c of puberty/growth spurt. She's 13 1/2.
you use bats? We just have the girls use there arms Saw a few in 12u we are 13u playing 14u and we have seen more in practice (season has not started yet)