I think there's more to it than that. Which of these names does not belong: Richard Nixon, Ronald Reagan, Algore. Richard Nixon conceded in 1960 and went on to win two presidential elections despite a defeat in the California gubernatorial campaign in 1962 - "You won't have Dick Nixon to kick around any more!!!". Ronald Reagan went on to win two presidential elections (in landslides) after conceding to Gerald Ford at the convention in 1976 (resisting the temptation to run as a 3rd party candidate).
Algore contested the 2000 election with dozens of lawsuits and lost and will never be president, even though 2008 was his year.
I do not believe Mr. Hoffman should have conceded, but I can't blame him for being a gentleman.
Al Gore lost the 200 election because he failed to carry his home state of Tennessee!
If he had won TN, he would have been president.
Walter Mondale won Minnesota (and DC) but lost every other state to Reagan.
Candidates ALWAYS win their home state - unless they are lying scumbags like Al Gore, JR.