Its a simple matter of supply and demand.
The demand for what these two are selling is shrinking.
Or.... it is a cyclical drop - being summer, with people being away on vacation, it being too far from the next election for real interest. Ratings fluctuate, and every time they do, idiots jump to conclusions as to why.
Let me know when the drop has been consistent, month on month, over another six months. Then there is something on which to hang your hat. Until then, all there is is enough rope to hang the stupid - and that, sweetie, is you.
You have hung yourself with your own rope.... I call it mental suicide.