It's a flawed stat, but PFF grades pass rushers on their "win" on the initial rush at the snap. It's like an extension of training camp discussions where we talk about DL X "winning their rep" against OL Y or vice versa. All those sacks against Washington would not count as pass rush wins because they were due to Sam Howell holding the ball too long. Why did he do that? Because the BIlls DBs took away his first read. In the end, it doesn't really matter. All that matters is that the defense made a play. But just like with PFF OL ratings, they are trying to quantify something that is not really quantifiable but because as humans we love numbers and rankings we eat it up.