Must win to not see a meltdown on CF.
Every game is important, but the only games are must wins are the ones where something is at stake. National Championship? Bowl positioning? Bowl eligibility? There are several ways to frame the question, and it ultimately depends on your goal.
The hope I have for the program (I would say goal, but I have no real direct effect on the outcome) this season is to get four or five conference wins. I hope to win them all, but the Big XII is a tough conference. Since there are eight more conference games after this one, I'm going to say it's not a must-win. And yes, they're all winnable games for their own reasons.