I have a slightly different perspecive than Aussie_coach. With boys specifically, growth spurts and "nature" have a significant impact even if they were once at the top of their level, especially in the age group you mention: 12-14. We have experienced & seen similar occurences: boys with immulate skills suddenly going through a major growth spurt, losing their centre of gravity (through nature) and having to relearn their skills again to accomodate for their new "longer", more muscular body. DS was high-performance elite athlete on the age-group national team at age 11. He decided to go back to the "mainstream" but, because of his skill level, was put in the 13-16 age group. Even with superb skills, there was no way he could compensate for the "natural" physical strength of these older athletes & he often finished much lower than usual; fewer ribbons/medals. Then his growth spurt hit with intensity. Longer legs made it difficult for him to maneuver some of the skills especially on bars. Fast forward to today at age 15 and, after 2 years of non-competitng to due a variety of injuries, he is once again placing & medalling; his skills have grown into his larger body it is a more level playing field. Having surpased nature's "physical" hurdle, he can now fully concentrate on skills building & get back on track. We have since witnesses similar scenario with many other boys in the 12-14 age group .... depending on when their physical growth spurt(s) hit! Not much you can do about THAT aspect!