dunking in a keyway that is open and you get 2 ( or 4) steps to gather yourself and then take-off is one thing, but to dunk through a crowded keyway where defensive players are actually trying to hinder you, and where you may have had only a one step "run-up" is another.
Tim Morresey could dunk spectacularly in the open court, and probably got higher than Mark Dalton or Chris Blakemore, but just like Kendal Pinder and James Crawford, Mark and Chris could power there way through hands that were trying to drag them down - thats a dunk.
Being smaller or skinnier gives points to the awesomeness factor, but the sort of power that means you can do it in traffic is respected more IMHO