The problem is that most people are results merchants - if a candidate wins, he ran a great campaign. If he didn't, he ran a poor campaign. However, elections are not like duplicate bridge where you play the same cards. The fact is Kerry nearly pulled off an upset - and might have if Bill Clinton had postponed his selfish book tour by about 8 months until after the election - or at least not criticized the Democratic nominee and others arguing against what Bush was doing in Iraq.
Bill Clinton had a third party candidate taking votes from GHWB and bashing him daily, while ignoring Clinton. In addition, where GWB was at 60 at the beginning of 2004, GHWB was at or below 40. In addition, it was a different media world - in 1992, the media WOULD have dismissed the SBVT pointing out that they were contradicting the official record, with no new proof - and that they were caught in lies.
After Clinton won, Carville and Begala wrote a book that became a movie that turned the campaign into myth. They created the view that the campaign responded to attacks better than anyone else. In fact, their goal was an answer - maybe complete, maybe true - but not usually. The fact is that on both the draft and Gennefer Flowers, Clinton had to respond at least three times - changing his story and finally admitting that there was some truth. In the anti-Democratic atmosphere of 2004, Clinton would have been killed by either the charges themselves or being caught not telling the whole truth.