It’s easy with hindsight to critique the conventional wisdom at the time given how hard Ohio swung right after 2012. But there was no reason at the time to believe that Obama’s position in OH wasn’t better than his position in states like VA and NH. As OSR said Obama consistently led in polls here (which turned out to be very accurate) while Romney was overestimated elsewhere. Romney’s auto bailout comments turned swing voters against him early in OH more so than states with weaker ties to the auto industry and that manifested itself in the polls.
I went into election night in 2012 expecting Obama to carry all of his 2008 states minus Indiana (which everyone expected Obama to lose), North Carolina, Florida, and Ohio.
It took no hindsight bias for me to see Obama in a worse position in Ohio than in all those other states, as I believed it was the case before any votes were cast.
I was half right; I underestimated Obama overall, but I had Ohio in the correct place relative to the national picture. I even correctly predicted Obama winning Virginia which Sabato foolishly expected Romney to win.
Sabato actually picked VA because he literally just tossed a coin and gave CO+NH to obama and gave the other 13 "tossup" EVs to Romney.