I would say most of what they do is a run concept with a box count RPO.
So first thing you need to do is read the box 7 vs 5 tells you you are running the ball on IZ.
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Now say they roll into a cover 2 and cheat the apex defenders into the box more you will see Martinez pull the ball more to a concept meant to exploit the numbers advantage elsewhere. This play was an IZ with a bubble to the bottom. I know some will have an access throw to the top of the field side, but I don't think Nebraska runs that much (if at all).
So basically most of their run concepts are tagged with options to keep the defense from stacking the box. It is on the QB to get to the LOS and determine where to look on any given play.
Now where I think a lot of Martinez's carries came from last year was when we couldn't get open or find them that caused Martinez to make something happen. Now I remember
@slattimer pointing out how he struggled finding guys in the NW game. Specifically Wandale over the middle IIRC. Later in the year I thought Martinez was better at getting through his reads.
Now they will run a QB dart where they like to bump motion the RB to a bubble. Martinez reads the box and either throws the bubble or runs the dart. When you had announcers calling QB draw it was actually this more times than not.
Here is a good video on it.....