because the detailed contract doesn't exist yet. When the contract extension was announced, the parties had only agreed on the broad outline of the agreement with the details to be negotiated later. At the time, outsiders said a "pro-rata" agreement was part of the outline but without any contractual language or details. Everyone assumed they knew what it meant... based on... assumptions.

Bottom line: B12 and ESPN are still negotiating the details for the ESPN part of the contract (Fox wants no part of the pro-rata stuff) and ESPN is going out of their way to let everyone know the media landscape has changed and they can't afford/won't agree to buying all the available content at the peak prices previously anticipated.