That's not how it's being interpreted by the Big 12.
2 years notice = an 50% hit for the two years prior to leaving. --> Big 12 withholds 50% of revenue for next two years. (~$5m per year for $10m total)
1 years notice = an 80% hit for the two years prior to leaving. --> Big 12 withholds 80% of revenue this year and seeks payment for 80% of revenue from last year. (~$8m per year for $16m total)
In that case, I am obviously wrong.