Simple, actually. You can't plug-and-play different players at different positions simply based on statistics and expect a better product on the field. A general knowledge of the overall scheme of a defense as well as the equally important yet still separate scheme of the defensive backfield is very important when evaluating talent. There are more than just off-the-field reasons why Pacman Jones was a bad signing in Dallas, for example, but since you're an expert on who excels at what, I'm sure you already know why.
It's difficult to even have a legitimate football discussion with any of you here because it becomes more apparent with each post that you both (and many others) literally know next to nothing about playing defensive back in football, or the defensive backfield as a unit in football.
I don't even know where to begin, whether it's the ridiculous screams of our lack of a pass rush for over half the season or the other, equally ridiculous screams to cut/trade/bench Terence Newman from 70% of the users here, despite your claims now of him having played at Pro Bowl caliber.
If you want to grade players individually, go right ahead. You'd fit right in to the Commanders's front office. After all, individual success is what brings championships to franchises....or 4-12 records and last place finishes in the NFC East.
I really am starting to hate fantasy football.