I really don't think it's a glitch per-say, as it is more of an exploit of the AI. There are people that lab these exploits to see how the AI reacts and to find the weaknesses where in conventional football they would be picked up, in Madden they look to see where the AI hiccups and makes repeated mistakes in positioning and judgment. Basically forcing any staunch offensive line to play well below their capability due to their AI shortcomings as well as forcing an offense to use hurry offense along with the shotgun and screen passes.
The ebb and flow of the game is dictated almost consistently by those fluent in the nano blitz and though an offense can counter it albeit with a slim margin for error, it really does make playing less enjoyable, lackluster and boring. It really isn't skill as much as it is research and repetition, it is akin to someone setting up a trick shot in billiards. It really just forces an offense to throw up their own form of repetative counter playcalling which makes the game even duller.
I enjoy playing a more encompassing playbook and strive to play more like real football and I don't lab but I do practice on occasion just to get a feel for plays I'm not too familiar with.
Everyone has their own style of play but I really take great delight in finding other enthusiasts who play the game without trying to take advantage of certain exploits at every given turn. Its seems the more competitive this game becomes the less enjoyable and the more apparant its faults seem to be. I really do think its time that more NFL games be made by different developers to see what progress can be made because they really havent fully realized or tapped into this current generation of technology, not just yet.