Was probably mentioned, but there's also just waaaaaay more entertainment options / things going on / crap to do these days, than ever before. There's not a "national vested interest" like there once was...
For me personally, if it's not the Bills (or maybe a marquee matchup near the end of the year), I'm not watching a Monday game. Maybe a few plays, but a full game? No way.
Same with Thursday - I hate that game. Pure cash grab that is fully evidenced by fact it gave them an excuse to invent a third Color Rush uniform. "Look - we brought you more ads AND more merch to buy!"
Also, they need to KISS with the distribution. I get the desire to sell rights to everyone, but Sun afternoon on Fox and CBS, but Sun night on NBC, then Monday on ABC? Or ESPN? Then Thursday on Twitter? Or some other such web site? Getting confusing for people...