Something to consider is whether an offense that is passing focused is as effective as a running based offense in the Michigan/Ohio State game.
I think an argument could be made that the team with an offense more running/power focused will generally have an advantage in a game played in a cold climate later in November. It's harder to throw the ball in cold weather (and then any precipitation/wind makes it even harder). Yesterday's game was played in cold/somewhat windy weather.
Even though Meyer's offenses put up huge numbers in the air against us several times, they also dominated on the ground (and generally ran the ball more than they threw it). The same goes for Tressel before him
Generally speaking, I don't think it is/was the wrong philosophy for Day to try to develop more of a power/running offense to beat Michigan. He just hasn't been very good at doing it.
Here's the other thing, I'm not sure OSU's offense was really all that great in general this year - especially post Oregon. Here are OSU's defensive yardage totals post Oregon:
Nebraska - 285 (averaged giving up 302/game)
PSU - 358 (averaged giving up 267)
Purdue - 433 (averaged giving up 452)
NW - 420 (averaged giving up 362)
Indiana - 316 (averaged giving up 245)
These are good numbers - but not great.