I want to outline a very simple, "cheap" concept that I refer to as the "look concept'. This is similar to a blog post written by @shotgunfball
I look at the field like chess pieces, much of moving the ball is trading pawns for pawns and one of the keys to making this work is making sure the defense displaces the same or more pawns than you do.
The "look" concept is a simple way of taking advantage when a defense doesn't properly align to your formation. I plan on using this a ton in trips, defenses are balanced, so when the offense unbalances (by going trips in this case) you force the defense to adjust in some way. If there is no adjustment and they align 2 defenders out over your 3 then you have the advantage and must take it.
Our standard rule on run plays is for our WRs to stalk block. We also have called screens we can run off of run fakes. The look concept is a combination of the two. We are running whatever run play is called, be it IZ/OZ/Counter/whatever.
The only difference is when we call/signal look after the play call it tells the QB to look at the defense over them. If there are 3 over 3 then the QB sticks with the run play. BUT if he see 2 defenders over 3 WRs he is throwing the bubble. When WRs get the look concept they know #3 is running the bubble
Now if the defense doesn't displace someone else from the box you have a built in answer, if they do you can keep with your running play you have called
Please excuse the 3rd grade level artwork below