This is not a vent board or any other kind of therapy. Before you hit the POST button, ask yourself if your contribution will add to the level of discussion going on.

Important notes on articles:

• Please do not copy entire articles into your post; rather, provide links to them.. We are now links-only for ALL Internet publications. If only a small portion of the article pertains to your post, Fair Use allows you to copy those one or two paragraphs, provided you cite the author's name and the publication for which he writes. Otherwise, put a link in the HTTP Link box.
• Even if you're copying a reference to an article, provide a link to the page from which the article came. We're trying to cut down on duplicate topics, and the posting process will check the link to your article to see if it's already being discussed on this board. At the very least, you'll save yourself some grief on the boards.
• If your first reaction after reading the article you're going to share is the author is uninformed / stupid / a jerk / all of the above, it's not worth sharing with anyone. Not every article needs to be discussed. The more the hair-pulling articles are discussed (e.g. ESPN Page 2), the more the authors will write hair-pulling articles.

Post being replied to

the LG, C, RG, and LT slide one gap to their left by jt

and are responsible for that gap if anyone comes through it and they do not chase a man; that's why in the video the guy talks about Nelson "looking for a looper." The RT is responsible for #2 on the LOS (5 technique usually, but can be a 7 or a 9 depending) and the back is helping outside to inside (probably should be vice versa but he doesn't pick up the blitzing safety and either way he's fucked in this scenario).

That's a 4 man slide. In a 3 man slide, the center "turns" the protection and slides in a direction with half of the line (guard and tackle to the side he turns it to) and the other side of the ball is in man protection--guard has #1 man on the line of scrimmage, tackle has #2 and they follow them wherever (preferably working as a tandem to pass guys off if there's loops/stunts/whatever). In a 6 man protection the back will be responsible to either get # 3 LOS or the backer at depth, usually inside to outside first (in other words, if both guys go, he takes the guy with the shortest route to the qb). In a 5 man protection the back is hot if one of those guys blitz.

That's why the qb and center identify the MLB pre-snap. Depending on the protection called they're either sliding to or away from him and it lets the back know where to go.