BCFToys front page has a chart showing the average drive data since 2007. This has existed for a while, but I usually just skip past it on my way to looking for specific data.
I looked a little closer today and saw some interesting things:
View attachment 14957
So the first is that PPD was just overall lower than I thought it was. I guess I became infatuated with the PPD stat during he CPJ era and just am so accustomed to numbers in the >2.8 range that I didn't think about average.
The second is the rise in the percentage of drives ending in "downs" beginning in 2018. PPD definitely has increased as teams have been going for it more, but I think there might be a ratio that can be improved to optimize it. One thing I definitely think about the analytics surrounding 4th down go/no go is that analytics are driven based on some factor of percent chance to get the conversion combined with the epa diff of each action. The one thing I think that is missing is in game success rate metrics along with the fact that neither the defense or offense seems to run normal offense in these scenarios. Anyways, my guess is that current analytic engines are overestimating 4th down conversion rates, but that is just my guess.
One interesting thing is teams seem to be more pass happy than in the past, but percent of drives ending in INT has dropped over the years.