What is the competitive advantage...

Easy fella, it's all gonna be alright

 

The alignment of the offense effects who the defense is going to cover for a possible pass play. Simply put it allows the defense to know who they have to cover. For instance if the TE is the only receiver positioned on the right side of the formation and takes a step back then the tackle on that side would be an eligible receiver. The defense could look at that and realize they need to cover the tackle.

 

The player on the end is deemed ineligible if he's "covered" up, (ie not exposed to the sidelines)... example, if in your formation a tackle ends up "un-covered" he has to declare as eligible... in order for him to not have to declare, a skill position player has to cover him as viewed from the sidelines...

 

There is none, especially if you're only a couple of inches behind the LOS

 

the competitive advantage is that you look at a formation to see who is eligible and who isn't pre-snap from the defensive standpoint... once you figure an ineligible receiver, you don't have to commit a defender to that guy... offenses line up in clever formations to disguise their intent and if the d isn't paying attention, a receiver who may have looked ineligible pre-snap can sneak out on a pass pattern and run free (the patriots did this twice in a row a few weeks ago)...