For the six MAC teams in Ohio, and I'm guessing the three in Michigan, literally nobody in those states is watching (or attending) MAC games on Saturdays when the Big MAC is playing.
I was still in school at Central when MACtion as we know it was first coined. My last rivalry game vs. Western as a student was played on a Friday night (when it rained sideways. I think my clothes from that game are still wet but I digress).
Here's the thing about MACtion. They actually have it timed out fairly well. The Tuesday and Wednesday games don't start until the first of November, which in many of these locations is when the weather has basically turned irreparably anyway.
Even then, unless you're in contention for the title, attendance for most of those games has already nose-dived. Yeah, some of it has to do with Michigan and/or MSU, but a lot of these students at schools like Central are going home on the weekends unless there's a special occasion, and freezing your ass off to watch a four-win team is not a special occasion. For example, Nov. 20, 2004, CMU hosted Ball State (in a game that pitted none other than Brian Kelly in his first year with the Chips against Brady Hoke in his second at Testicle Tech). Chips spotted BSU 27 points, then pulled them all back by halftime and ended up winning a 41-40 thriller. I'm pretty sure my roommate and I had a lot of wide open space in the student section to get behind the guys, and that we did. I don't think I missed a home football game in five seasons in MP (graduated in 4 1/2 years).
Attendance? 10,169. Heck, even when the weather was decent, CMU's only other non-rivalry conference home game that year was on Sept. 18 and drew 12,292 against Kent State. That CMU team went 4-7 (Ball State was 2-9) and had both Matt LaFleur and Robert Saleh as grad assistants.
My point is MACtion kicks in when the value of the inventory sinks to such a level that the value of getting uninterrupted time on an ESPN network supersedes that of having an even meager gate.