Without a bowl appearance this season (5 in a row), this staff is on a 12 month performance plan, period. Consistently falling short of expectations is one matter (Division competitor, occasional upset win, etc.), but outright failure is another.
Missing a bowl game for the 5th straight year when you are collecting a $5 million annual check is deserving of scrutiny and consequence. With your generous timeline, he might as well construct a hammock and allow the assistants to coach the team for the rest of the season. Who knows, they might perform better.