That's actually not true at all....PFF uses a simple +/- scale that actually takes on the exact opposite of the scenario you mentioned. Under PFF's system, all downs are going to be weighed equally. It's why a guy like Diggs makes so many explosive plays but has a terrible PFF grade. An 80 yard TD pass by Dak is valued almost the same as a well executed screen pass that goes for 8 yards.
PFF has it's shortcomings, but it sounds like your friend hates PFF just because they want to.
Here is an small piece from the PFF article this thread was based on about how they score for these rankings, and it is mostly metrics based entirely on situational football.
"In rating offensive play callers here, we use PFF grades — adjusted for opponent and scaled for age (most recent games get the highest scale — and, probably most importantly, we take into account expected points added and success rate going into the games and plays of interest, which also controls for situation."
It goes deeper, but dont want to violate the rules and post too much of an article that I'm assuming is behind a paywall? Anyways the biggest flaw this article has is it rewards pass heavy teams over run first teams, which probably plays into KM's ranking especially for the back half of the year.
Certainly not perfect, little that PFF does it perfect, but it's an excellent tool to use and an interesting read.
