First, Ford was not running for "reelection," he was running for a full term. He was the first (and so far, only) person to serve as both president and vice president without ever being elected to either position.
And second, Ford probably could have won if the campaign had just lasted a few weeks longer. He would've had more time to make his case, especially considering that he was facing major backlash against the GOP over Watergate.
I agree on this point to a extent.
Well, I also agree with that. He was trailing by thirty points after the convention and got within the margin of error on election day. That's tremendous.
However, I'd define "reelection" if an incumbent is running for the office he currently holds. What I guess that's a question of definition.