Sure, Reagan was always going to win, but I feel like Mondale could have done much better. First of all, from what I've read, they held back on negativity towards Reagan because of his personal favorables. This seems idiotic, if your opponent is popular you should go all the more negative, since driving their numbers down should be your priority. Also, it seems from the ads he emphasized the deficit above all else, something most voters don't completely understand, yet alone care about. The second biggest issue was arms control, another loser for the Democrats in this period in time. I feel like he could have done a lot better by emphasizing jobs and healthcare.
I'd be interested to know the source, and if it's true. Though I was only 18 (as of Sept.) I remember Mondale (and other Dems) throwing everything including the kitchen sink at Reagan: he was inattentive (Beirut Oct. 23, 1983) and possibly too old; he didn't care about the poor; he was a militarist; he was out of touch on issues like abortion. Then again, maybe I just got that impression because I was living in Cambridge, MA (which voted Mondale 76.2% - 23.4%) at the time.
Oh yeah, I almost forgot, Mondale opposed the death penalty, favored by 70%+ of Americans. That couldn't have helped him.