PFF grading system appears unclear

The thing is why should we care about an arbitrary grade from a 3rd party when the professionals don't? Coaches grade their players because they know what to grade them on and other teams use tape and scouting reports to prepare for their weekly opponents. So can PFF grades really be a tool if the people who the tool matters to is more accurate? PFF grades are for media and fans only..lol. The problem gets to the last point; people using PFF grades as gospel.

That said, I will never put down the objective data that PFF provides. Their analytics are pretty top notch from what I've heard.
Of course it's for the fans. I cant speak about it professionally, but apparently people use it. If you don't care about performance metrics than yeah you wouldn't care. If you do, it's the only available metric that actually reviews film. Most fan don't have time to watch film on players.

Just as much as you can disagree with someone's film evaluation, PFF can be wrong. Most of the time it's pretty clear win loss. Over time you'll get a decent idea of their performance.