[Defensewins]

Sellers is a great pick up!
One thing about Gibbs old system, while he does like the one back - two tight end formation, he uses multiple formations and alot of shifting. He does not stay in one formation for long. He likes to try and confuse the defense with multiple sets.
Then as the game progresses he will go with what is working. So I think all this worry about the H-back and tight end positions is over kill. They just need to be good blockers.
The QB, WR's and RB position is the most important to Gibbs system. The reason is his pass plays have many sight adjustments. On a certain percentage of pass plays Gibbs will call a formation and a play, but depending on what type of defense the DB's are playing, will dictate the route the WR will run. This is not an audible, because the QB or the WR's do not communicate the route before the snap, like in an audible. The WR has the option of running one of two routes. If the DB plays man to man defense the WR runs certain predetermined route. If the DB plays zone he runs another predetermined route. One of two options. This takes great skill and concentration so the QB and WR are on the same page. It is very easy to look bad. But when it works....watch out!
Oh, they determine what defense the DB's are playing by using alot of motion before the snap. Gibbs system has alot of motion. It is a complex offense, which is why Gibbs prefers a veteran QB.