Such experienced pols/pundits as Newt Gingrich have been saying that the idea of a few states controlling, apart from the whole electoral college and popular vote, is bunk.
Newt pointed out that states don’t go wildly opposite the rest of the states, or opposite the popular vote, but fit in within a historical trend and with other facts of the vote.
He’s not talking about polls well before the election but the actual vote.
He also does not believe in aiming a campaign at each of several individual “swing” states as if that would pull the country along. Instead, he says the country as a whole and the swing states will tend to perform collectively and individually “in sync”, therefore run a national campaign WELL, and the necessary states will come to you ON ELECTION DAY.
McCain ran an awful campaign, and he was up against a candidate that mesmerized the country with youth, teleprompter speaking ability, the first Black potiential president, etc. Yes McCain won certain reliable Republican states anyway, because the nation IS divided along somewhat reliable lines.
But the reason he saw Indiana, NC, VA, FL, OH etc slip away ISN’T THAT HE FAILED IN THOSE STATES BUT THAT HE FAILED NATIONALLY.
While a lot of what you say is spot on isn’t also true that there are just a lot of states that you are never going to turn over. Many will always be blue and many will always be red. As it got closer to voting time it was easy to see that McCain could not carry the states he needed to give him a victory. All but the most ardent GOP supporters could see that! People were doubting the numbers coming out of the polls then as they are now but the old wise ones of FR were could see it simply that he was not carrying the states he needed. So i think polling out of these particular states might be a better indication than the country wide one especially if the difference is inside the possible margin of error!