There's an old principle in football that the most popular guy among fans on any team is almost always the backup quarterback. Almost no matter how successful the starter is, there is always a large and vocal contingent of fans who think the backup should be starting. If the starter ever gets hurt in a game, these fans will cheer at the sight of the second-stringer entering.
Unfortunately for the hopes and dreams of these folks, there are usually good reasons that the backup is the backup and the starter is the starter. After a few games with the #2 guy at the helm, those reasons start to surface, and people realize things were not so bad under the top guy. It can be easy to get used to tight spirals and laser-beam medium-range throws to the point where you sort of forget why those skills are important.
It doesn't take too many quarters of watching a noodle-armed backup throwing two-yard square-ins to the tight end to remember that, while pluck and derringdo are laudable characteristics, it's often nice to have a skilled professional at the helm, somebody with a big arm who knows how to use it.
For all John McCain's positive qualities, there's a reason the guy lost to George W. Bush. He's got backup-quality skills. He's fun to root for! But you know deep down you don't really want him running the team.