I understand that he saw Casamyora as his mentor, but he was not fighting a smart fight. I'm glad he was knocked down in the last round. I hope that helps him as a fighter by reminding him not to fight dumb.
To answer this question, you need to establish what his marketability was before the fight. Due to inactivity, plenty of casual fans won't have heard of him. Now they might.
Guerrero had an old Casamayor in front of him and proved he was much better that night but he let Casamayor hang around anyways. He should have pressed for a stoppage and getting knocked down at the end of the fight added to his troubles. Guerrero isn't going to be a star but an impressive stoppage of Casamayor would have gave his career some momentum.
