As someone who was once a very talented young runner, these comparisons are useless at best. Some of the best runners I've known were unexceptional until they were older (and physically mature) while others excelled as freshmen/sophomores and never improved by more than a few seconds. While I think our understanding of training has improved over the years, there are still things that are too difficult to perceive in an athlete to truly evaluate their potential at such an early age.
Apparently Ron W told Hobbs he could break 4 before Hobbs had broken 4:20 but Hobbs is a generational freak talent who probably showed some spectacular talent in practice and Ron W has more coaching experience than most of this message board combined.
My point is, when training works, we do a good job of explaining what's so good about the training. When it doesn't work, we can do our best to pinpoint what went wrong. When a phenom freshman never improves or improves only marginally? That's a much more difficult question to answer and sometimes it is never answered. What makes someone good is way more complicated than how fast they are at x age and the best thing you can do is just get the kid on a consistent training plan that doesn't break him before he has any chance of running sub 4.