The decline from the 2005 peak was inevitable, and over the next five or so years a lot of those fad fans (among others) did walk away. But from 2010-2013 there was a plateau in the TV ratings; they were generally stable from year to year. Things didn't decline again until the 2014 season and I think you can certainly attribute a good amount of that to the championship format. 2017 will mark the fourth straight year of the second decline period, and again, I think you can attribute an amount of that to the new race format. Certainly the new TV contract in the time period didn't help, as FS1 and NBCSN don't compare at all to the subscriber figures ESPN and TNT had during the previous contract. I'd say all of the above are pretty significant factors.