You could probably cut out half of the PAC schools (with the right cut) and still retain 80-90% of the PAC's media value. Merge that into the B1G and you could justify the move.
The PAC paid out about $370M last year. With the right mix of PAC schools, you could grab $325M of that value (6 schools x $54M) and move that inventory over to the Big Ten. The Big Ten wins with a massive expansion into great markets and new inventory (10pm ET start times).