Caroline won her Junior World Title as a teeny 13 year old though, before she went through her big growthspurt. Most of the medal favorites this year are older: Christina is 16, Agnes is turning 16 this summer, Kanako turned 15 in the fall, Kiri will be 15 in a few weeks, Polina turns 15 over the summer. Only Anna and Polina are still 13, and they turn 14 in March and April. I think a lot of Junior Worlds success and what it means for the skater's in seniors depends on if they win their junior medals before or after they've had their big growth spurts. In the case of the top 2 here, I don't know if Kanako and Anna will grow a lot more or not, they could, but they look pretty well proportioned now so they might not get much taller and just fill out a bit in which case they are less likely to disappear on the senior level then the girls who might grow 4 inches between now and when they move on to the senior level (what happened to Caroline).
Great point! Many of these phenoms are just not going to be as good jumpers after puberty and/or their true adult size. Oksana was not nearly as proficient once she got the curves. Others like Kwan were total work horses with great coaching and solid fundamentals