Perfect example of a Benjamin button chin is George foreman. Deterioration example would be let's say DM or even Golota if we're sticking with the polish theme. More examples?
Robin Reid had a seemingly solid chin for 3/4 of his career and then he just started getting dropped and stopped constantly.
I think Maskaev showed the whole range. Resisted punches that should have stopped him. Stopped by punches you though he would have resisted.
Pacquioa was stopped by a jab,.. then spent most of the latter half of his career walking through flush middleweight haymakers. In the end, against a reinvigorated JJM,....Pacquiao ........couldn't take his own punch.
Nicked that last line from you (with apologies)… but yeah, 'justice served' under the jurisdiction of the commission,…..this bout reminded me of that old game 'Mech-warrior' back when we waz chopping it up on the Atari.
