All teams are not created equal in terms of togetherness and oneness. There are lots of disjointed teams out there and it tends to show up at critical points in a game.
I don't think you can manufacture or coach togetherness. On a typical team, you have groups of friends, mostly within units or roommates, and there are individuals and groups that don't particularly like each other. Sometimes they despise each other. I've seen some exceptional player leaders be able to bring different guys and groups together, or at least lead them to set their issues with each other aside to pursue team goals.
The highest degree of togetherness, unfortunately, is usually the result of a tragedy or some awful challenge. In 2014, I don't think Ohio St was playing at a national championship level until the week of the scUM game when a walk-on DT went missing. A day later they found him in a dumpster, dead with a self-inflicted gunshot wound. Suddenly, despite playing with a troubled QB who didn't come to play school, after mourning together they beat the crap out of Wisky, beat Bama, and thumped Oregon.
I think scUM has togetherness due to what they perceive as the persecution of their coach and everyone being against them. Whether that's real or imagined, it doesn't matter. All that matters is that they believe it and it has caused them to circle the wagons and fight for each other. That's powerful in terms of team dynamics. It elevates a teams level of focus and play. Effort goes up a notch. A higher purpose than doing it for myself is a powerful force in team sports and scUM looks like they have it.
I'd bet Ohio State's preparation was excellent. I suspect they weren't quite as together as their opponent was. FWIW