Alabama opened the 2009 season by beating Virginia Tech 34-24. When that happened, I doubt there were many college football fans—LSU or Auburn fans aside—that had any doubts about the Tide marching right through their schedule and into the SEC Title game.
They proceeded to do just that, thus further establishing Nick Saban (and whichever team he's coaching in any given year) as a constant and gigantic presence on the college football landscape.
Meanwhile, in the Big Ten, while Iowa had a number of close games, they really seemed to define who their program was in their game against Michigan State.
A back-and-forth, low-scoring, primarily defensive game, punctuated by an exciting, last-second victory for the Hawkeyes.
On the other hand, the makeup of Bob Stoops and Oklahoma seemed to be defined early in the season, in a game against BYU.
In a game in which the Sooners' Heisman-contending quarterback went down with a shoulder injury, the young o-line took penalty after costly penalty, and Stoops made some questionable decisions , OU wound up losing 14-13.
The rest of their season was a mess of close losses and opportunities wasted, and ended with an 8-5 record. Certainly, eight wins wasn't awful, but it was quite a comedown for a team with National Championship aspirations.
Ultimately, every program has to define itself year-in and year-out.
There are programs with questions, programs on the way up, programs on the way down, programs looking to maintain their status, and some coaches looking to hold on to their jobs.
This list is made up of games featuring programs that will have some questions to answer about who they are. Moreover, those programs will look to answer those questions at the expense of their opponents.