Ok, Im gonna try to one more time to help you understand. First things first, I want to point out that you are arguing with fact. Which is just about the most impossible thing to do. Its like trying to argue that if you flap your arms really fast that you can fly, and when everyone is presenting you with evidence to the contrary, you just say "yes I can, dont get mad cause I think differently than you". It is a FACT that NFL playbooks are extremely complicated, with thousands of play variations. It is a FACT that knowing your assignment for a lineman is absolutely imperative.
Second, I just wanna point out exactly how contradictory your argument is. Repeatedly you have stated that all he has to do is block the guy in front of him, or closest to him and everything will be ok. That is exactly what the Cowboys and HH are trying to teach him NOT to do. That is Denvers scheme, that's what zone blocking is, you have a zone in front of you that you are supposed to not let anyone penetrate into. If no one threatens your zone, you move downfield and get to the second level. In Dallas scheme, its a MAN scheme, which means you specifically have someone you have to block, and its not always the guy in right front of you, the most obvious guy, or the guy you would think you should block on a given play. In fact, the very best running attacks use many many different blocking variations to throw off the defense, AND, the LG just so happens to be the one who has the craziest assignments because he 99% of the time the uncovered lineman.
Offensive line play, despite its brutal nature, and rugged appearance is very very choreographed. Im talking all the way to the most minute detail. Everything from exactly, and I mean EXACTLY how far apart you spread your feet, and how far your left foot should be from the guy next to you's right foot, to which foot your supposed to step with first, and in which direction. If they feel the need to choreograph those tiny tiny little details, you dont think there is a chance they choreograph the rest of the play to the max? I assure you they do.
Lets go through a very very simple dive play. Lets do a weakside dive so Montrae will play a key role. The idea of this play is to get Barber through the A gap, between Montrae and Gurode. We'll do this out of a standard strong right I formation. The most basic way to block this play is to have Bigg release to get the backside ILB, Colombo handles the backside DE, Witten handles the backside OLB. Playside, Flozell drives the playside DE out, while Cricket kicks out the playside OLB. Then, Montrae and Gurode double on the DT, with Montrae releasing to the second level after a split second delay. Now, I can think of 9 other completely different ways to block that play, and Montrae has someone different to block on 5 of them. The Cowboys most likely use 3 or 4 variations of the simple dive run versus a standard 3-4. If Montrae doesnt go get his guy, Barber gets lit up in the backfield. Its not about "just blocking the guy in front of you". I would bet anything, there are at least 500 run variations in the Cowboys playbook, there is no way he can memorize them all in one week.
Last thing, real quick. The thing you seem to forget the most in this whole thing is terminology. Even if the Cowboys and Saints blocked everything the exact same way (which they dont), the terminology would be completely different, he still wouldnt understand what the playcall was in the huddle. You have to know your assignment as an OL....please take it from me man, as I told you before, I was a offensive line coach for 5 years. If there is one thing I really get, its offensive line play.