I'd like to postulate a theory about picking the winner of a presidential contest..... (wait for it)....
Picking teams in dodgeball (I'm 46 so we played that often back then) was a curious combination of popularity and perceived ability. If you were popular and could throw well, you got picked first. After that round, it usually devolved to picking the most popular, followed closely by able bodies. The remaining kids were usually the geeks of the crowd who would grow up to be wealthy computer nerds, but (lets face it) weren't popular at the time nor could throw worth a poop.
Flash forward to adulthood. Picture the American people as the kid in charge of picking the people for his dodgeball team on the playground in 5th grade. Who would he pick first? Let's look at the last few elections and see if it holds true:
Trump vs Clinton: Trump for sure. Not sure if Clinton would be able to throw a dodgeball. Then there is the whole thing about no one really liking her very much.
Obama vs Romney: Obama would certainly kill it over the stormin Mormon. Plus no one really liked Romney other than his fellow Mormons and despite their efforts to the contrary, they are still a tiny minority of the population.
Obama vs McCain: Obama would run circles around McCain. Obama's lucky though as McCain would certainly get him if they got within knife distance on the field. McCain also couldn't shake his 'rogue' running mate, nor Bush's poisonous influence.
Bush vs. Kerry. Certainly closer, but Bush definitely had the scrappy factor going for him.
Bush vs. Gore. Extremely close, and evenly matched on the field, but Bush had some popularity going for him that Kerry couldn't shake.
Clinton vs Dole: Close, but Clinton had the clear popularity win and could have taken Dole on the field as well.
Clinton vs Bush: Clinton had the clear field advantage there and popularity as well.
Bush vs Dukakis: Pretty level on the field at the time, but Bush was riding on the wave that was the Gipper's popularity.
Reagan vs Mondale. Mondale could have taken him on the field, but Reagan was a clear popularity contest winner.
Reagan vs Carter: Pretty level on the field, but Reagan had the dominating popularity advantage.
Ford vs Carter: Ford had a domineering field advantage, but couldn't shake off the crook's baggage. Frankly it really didn't matter who the democrat's put up, they would have won.
I'll stop there as I really know nothing about McGovern other than the fact that he was from my home state of SD and the fact that I'm back 40 years now. I suspect that this isn't a perfect theory, but pretty good nonetheless.
I will say that if the democrats want to regain the white house in four years, they better damn well put up someone who is both popular (think Kennedy popular) and can throw a dodgeball like the wind.