Sean O'Grady once said, "The chin is like a cash register. Eventually it fills up and can't take anymore." Or something like that Cobb's chin reached that point against Collier and he was done as a legitimate fighter.
I was just reading his bio on Wiki and I see he is not credited with a small acting role he had in Any Given Sunday, which starred Al Pacino and Jamie Foxx, among others. It was just a very small scene that lasts maybe a minute, but he was still in the movie. In the 'making of' bit, Oliver Stone says that Cobb's face could only belong to a fighter.
I only thing I remember Tex saying about the Collier fight was "I was incredibly clumsy". I saw a interview with Tex prior to the fight and he said something about possibly getting a shot at Michael Spinks. Almost positive he didn't throw the fight with a possible Spinks fight on the horizon.
Yeah I can't believe he threw the fight. Fighters like Cobb pride themselves on their toughness and it's essentially what he was known for. To throw that away in a nothing fight against a competent but unspectacular fighter like Collier...?