I have heard of buck regressing and seen a few claimed examples, but never seen one go back to a clean fork. The claimed examples I have seen were all real heavy multi-point racks that looked stunted and had alot of trash points.
For blacktail on the coast we see quite a few bucks that never seem to grow any more than forks. They just get heavier and wider/taller each year. We call them Pacific forks.
Of course I have no scientific backing for any of this. It is all just seat-o-the pants armchair theory.
Here's an example of a blacktail: