I've seen a good junior player went from UTR 6 to 8 in a very short time, but I think it's more to do with the system than actual skill improvement. He has very good counter puncher style games (i.e. no pace, good timing, good speed), and he wins a lot, when he plays against a 6 or 7, he would beat most of them in a 6-4 6-4 score line, and when he plays an 8 or low 9s, he can still manage to get through with 7-6 7-5 score lines. He manages to get close scores against those in 8/9 (but not 10s) in most matches, so he decides to play more adult tournaments and it feels like he's improved, and UTR's gone up by 2 just in just a few months. UTR is right in that sense, but I'm still puzzled and perhaps not fully convinced.... UTR predicts the score line, but not so much the ability or skills one might think.