what i can tell about training from my practice is that i managed to get 8 pops in passing per season in 6.8 height 18yo guy with llv 5 trainer. Also managed to get 5 js pops to 6.10 guy who also was 18 years old, so height doesnt really matter, age defitenely does, since the time i was training passing my small men got 6 and 7 passing skills respectively at ages 20 and 21:D and at aes 21 and 22 they got 5 js pops each per season too.:D