Disagree a bit. There are a ton of read keys which dictate where they position themselves, shade and go. They include TE, Slot, FB, HB, QB and WO alignments, and their and OL movements off the snap. Each player has his own key reads that work in concert with others. When Edsall says “do your job” that’s what he means. Get to where you belong and execute. If somebody misses his “assignment” then things go bad. You work out of base defensive sets and adjust week to week on keys and assignments based on your opponents personnel, offensive tendencies and associated strengths and weaknesses. What I have maintained and believe is there is a big difference between good athletes and great football players. Good football players more than compensate for speed and even strength with better on field intelligence and skill. Football is not a track meet. Our DBs are athletes and can run fine. They can’t anticipate, take good angles, can’t get around on a pass or tackle very well.