I think the main difference in what we are thinking comes down to differing definitions for “Top Coach”, I’d reserve my judgement in labeling a coach “top” even if they had developed standout athlete, until they were able to develop another. Sometimes talent outshines a bad coach, so long as their methods are relatively benign.
It’s funny how in our sport young athletes tend to regress after a change in coaches (even if the new coach is a good coach). Swimming has a model whereby the athlete will be “passed up” the chain of coaches as they get older and develop. Even removing the personal dimension (which granted is not realistic) I don’t think this would work in sprinting. It seems as though sprinters are so idiosyncratic and differences in performance o fine that, aside from the odd exception, a change will nearly inevitably lead to a decline in performance. Even if the transition is smooth and amicable, there is sooo much information and specific experience that gets lost in the transfer that the new coach faces an overwhelmingly steep learning curve and high expectations.