I was thinking this earlier today, and here's my rationale:
I think this could be considered Bo's biggest game for a few reasons. It's true that this doesn't directly affect our championship hopes, so the tangible stakes could make it bigger, but this is a very specific type of big game for us.
Since arriving in Lincoln, Bo's teams have struggled in two ways more than any others - staying consistently motivated against lesser opponents, and getting up for big games on the brightest stage.
The last three years have exposed a lot of leaks that I think Bo has done an admirable job of recognizing and growing from - I don't think for a second this program is in the same place it was entering 2011. But we continued to see some of the same trends. This season, however, has the pieces in place, including the irony of Bo's two biggest obstacles in consecutive weeks. The team came out amped but under control to handle Miami, then came out with consistent motivation against inferior Illinois, and now is poised for the biggest game of the year against the best team on the schedule and the hardest regular season game we've had in several years.
If they are up to the task and come out with a victory, it will be Bo's biggest game without question because it will be his greatest triumph. If they don't, then who knows.