|Patrick Semansky / AP|
Let's start with the simple task of not pulling a player. This provides one fewer key for the defense. Now, that seems simple, sure, run a zone or iso or a lead play and there isn't the pulling key. But what if you want to maintain the numbers advantage provided by a pulling blocker but you don't want to provide the key? That's where inserting multiple backs into the action can help.
Here, Michigan runs something that I call "Power F". Essentially, the FB acts as the pulling guard as the H-back acts as the kick out block (note the gaps formed below are the same gaps that are formed with a power play.
Note that on this play, the playside LB takes a false step then attacks the "pulling blocker" with the wrong shoulder, opening up a crease in the defense. Similarly, the backside LB gets caught up instead of getting across the formation.
Here's something that is criminally underutilized in modern football: the fold block. In fact, I haven't yet seen Harbaugh utilize this tactic, but I want to talk about it because it's something that I really love. The fold block is used to improve blocking angles for the OL while allowing an OL to be a lead blocker similar to a FB. If you have a OL with good feet, this can be deadly. You can also use it as a counter to the Power play.
Here, instead of attacking the "frontside" LB, the pulling blocker will actually be looking to attack the backside LB and the frontside takes himself out of the play. I've shown it below both against an Over and Under front (notice that the blocker changes from the backside guard to the center, which can sometimes be difficult for the center when the QB is under center, so the RB needs to allow the play to develop before getting down hill).
This play is perhaps even better served by a team that runs a lot of open side (weakside) Power, as seen in the next two diagrams.
You can also run this like a "G" play, with either the FB or RB (though that is a frontside pull)
While not Michigan, here's former Toledo coach (now Iowa State coach) Matt Campbell running a Center fold with what could be a read option on the backside of the play (both open and closed side)
Ian Boyd talked more about it here.
A reemerging scheme in today's football is the "Wham" block. What hasn't yet reemerged with most teams is influence traps and whams. An influence trap cause the frontside of the defense to overplay the outside run, but the backside pulling blocker will still provide the backside players that "pull" key. So we'll save that, and focus instead on the influence wham play.
Here, you pull two OL, one gives a false "frontside" key, the other a false backside key, and forces the defense to react opposite where the play is actually going. The H-back then cleans up the defender covering one of the pulling guards. Not only is the DL flowing the wrong direction trying to squeeze out the pullers hole, but the LBs begin flowing the wrong way as well.
Pull a Guard - Cut Back
Of course, there is always the option of stressing the cutback to the RB if the backside is overpursuing. If the backside LB is getting himself down into the wash and committing himself to the front side play before the RB gets to the LOS, the RB can check for that over committal and cut the ball back across the gain for a nice gain on the backside.
While not the same, the trap play works in a similar way. Rather than sealing the defense on the backside, it seals them on the front side once they get over aggressive.
Pull a Guard - Play Action
A wise coach once told me "if you really want play action, pull a guard".
This works to pull LBs out of their run fits and out of their underneath zones. It's also highly effective at forcing safeties that are involved in run fits to cheat down or lose their spot on the field. Harbaugh has consistently taken advantage of teams that try to heavily utilize safeties within their run fits in this way.
And here's a great example of the pulling guard freezing the safety and allowing the WR to get behind him (wait for the replay).
Pull a Guard - Boot
Or, of course, you can always run boot action. This play is a designed QB keeper all the way. The Michigan defense is overloading the front, so they still have a free hitter, but he takes a poor angle because he is anticipating crashing on the RB from the backside of the play. More importantly, look what it does to the ILB that would be the backside ILB against power.
Michigan is going to pull blockers, it's a key facet of their offense. They love to get additional bodies at the point of attack. But defenses are going to use those pulls as keys to get extra defenders to the point of attack as well. They key is to find the balance so that the defense must play honest. By having these counters to your standard pulls (Power, Counter, Trap), you force the defense to hesitate a bit and respect the backside run or the play action. In a downhill, power run scheme, that can make a huge difference in allowing for success.