1. You're considering ALL Big 12 distributions. Tier 1, Tier 2, Tier 3, Sugar Bowl, conference championship etc.  That gets them to $42M
2. The article cites $30M per team with the PAC selling a similar portion of their rights as last time.  Which is Tier 1 and a small amount of Tier 2. 

So that $30M would actually be ahead of the $22M listed here.

That said, the estimate from SicEm also is (as best I recall) outdated and has been replaced with a higher value