Average. His defense was poor. Even if he had an Ali like chin, he would still have been tko'd a couple of times due to how many flush shots he took.
Was his defence poor? Cooneys problem was he was virtually a part time boxer. I’m not giving him a pass on that, but a seasoned fighter copes much better than an inactive talent in competitive fights. Gerry had one round of work to 21 rounds that Larry got over the same period. And that was supposed to be cooneys prime.
I've seen precious few fighters whose chin I would say is actually glass. Probably less than ten across all weight divisions. Cooney's chin wasn't glass. It was so-so.