What would you say is the weakest chin level after glass?
Id put Tim there.
And you are basing this on what? I quite honestly think you're just making things up at this point to justify your opinion.
Ray Mercer might be old, but he is still a professional boxer who was a heavyweight champion at one point. Getting KO'd by that is hardly proof of a weak chin.
He got dropped by Fedor, the best heavyweight in the world who has some monster shots. He got dropped by Couture, who has pretty good power. He got dropped in two fights against Arlovski, one of the best pure strikers at heavyweight, and big old messy Tim managed to recover from one of those to win the fight. So please, where are all the other big KOs that Sylvia has suffered to prove what a poor chin he has? All the other times he was dropped in a fight?