http://www.thesweetscience.com/boxing-article/8086/referees-strike-out-yankee-stadium-cotto-foreman-card/
George Kimball had a good account of what happened.
He's right, Mercante was not acting professionally. I understand, fans want to see a fighter carried out on his shield and they feel ripped off when a fight is stopped when a guy is still standing, but when it's obvious a guy is trailing badly, taking a beating or his ability to defend himself is seriously compromised and he has no realistic chance of scoring a late-round KO, stop the fight.