Perhaps it is worth noting that by every estimate Reagan lost his first debate to Walter Mondale in 1984. Even Reagan's handlers conceded Reagan looked old, tired, and out of touch. The election that year was the biggest electoral landslide in history.
And same in 2000. Most thought Gore won the first debate. It was the third debate that did Gore in.
I dont think the situations are the same. Reagan was a very popular President and we werent at war. Plus you forget, Mondale proudly told everyone that he was going to raise their taxes.