PPP seems like a so so determinant for offensive efficiency.
Essentially, it rewards big plays and not turning the ball over - which is all good. Buuut, it does not factor in time of possession (which we clearly just try to run clock sometimes), starting field position (starting further from the end zone means a worse PPP?), whether we are in front on the scoreboard (obvs running the ball and taking more plays)...and other confounding variables that would seem to greatly influence PPP
I think it provides a decent order of magnitude type of comparison...but thats it.