Howard Dean/Wesley Clark ticket would have done better than the Kerry/Edwards ticket due to whatever Equality Marriage did to the ticket in 2004, not 2014, and Teresa Hinz-Kerry damaged Kerry as well.
Kerry ruined any chance he had to run for prez by promoting a preemptive war with Syria, with the Democratic base, based on the same weapons of mass destructive argument he used against
Bush. He should ride into sunset.
Gay marriage wasn't really a winning issue yet in 2004, as a majority of people did not favor it until 2011. I don't see how campaigning in favor of a position that most people opposed at the time would have helped Howard Dean if he was the Democratic nominee in 2004.