The downside of doing this is that it gives the defense "keys", particularly for the LBs, who are often taught to read through the OG to the FB. A pulling OL typically leads you to the play, a FB often leads you to the play as well. Of course, utilizing both Power O and split zone helps Michigan break one of those reads, but if you want more blockers at the point of attack and don't want to tip your hand by pulling OL, what can you do? More backs is the answer. Let's take a look.
Basic FB Blocks
Michigan will utilize their FBs in a couple standard ways. From a previous article
Inserting a FBSo already, you have a couple instances where the FB takes the defense to the play, one where he goes away from the play, and can be inserted anywhere along the LOS (obviously, he could also lead block on the weakside of the formation). This all leads to Michigan's base play.
By utilizing a FB, as an offense, you lose one of your vertical threats in the pass game. To make up for that, you add to your run gap multiplicity. By starting behind the LOS, the FB can be inserted into the play to add gaps along the LOS.
A Power block adds a gap outside to the playside of the formation. Typically, the block is a kick block, and that opens up a gap inside of that kick block; however, sometimes the block arcs inside and the RB can bounce. The point is the same though, a gap is inserted on the playside and outside.
A lead block also adds a gap to the playside, but now it's on the interior of the formation. Typically, this forces the LBs to adjust on the fly in order to defend the gaps. Of course, prior to the play, they don't know where the gap will be inserted into the formation.
In the case of split zone, the gap is added to the backside of the formation. In this case, it makes it difficult for the backside of the defense to crash down on the play and close other interior gaps, and opens up the cutback run for the RB.
Plays like Power O (or counter F/H) flip a gap to the point of attack and insert an extra blocker to the playside. Essentially, the playside adds two additional gaps post-snap in the C and D gaps. The defense, of course, has to be able to account for this after the snap.
That's two new gaps at the point of attack, and gives the ball carrier some really nice option once he gets there.
Power Lead is the same play as Power O, except instead of pulling a backside OG, you replace that pulling blocker with what is essentially a pulling FB. This "pulling FB" is your "Lead blocker". Make sense? Eh, let's look at a picture.
Notice the gap options are exactly the same. In the play, the first FB has a kick block, the second leads through the C-gap. Now see it in real life.
Same play, different keys.
Traps and Whams
Of course, one of Harbaugh's favorites are traps and whams. Again, these are essentially the same thing, but one trap blocks a DL with a OL, the other with a FB, and both add an additional gap, this time in what was once the B gap. (note below: the purple lettering means that gap goes away because the blocker is pulling out, thus only leaving one gap in that area)
With video (note, the FB is inserting himself where the pulling OG comes from, so thus the B-gap is retained)
And with the Wham
Watch the play, the FB (here, an H-back) inserts himself as the trap blocker, kicking out the DT (while the OG retains his typical gap block).
Lead Trap and Wham
But what if we still want to isolated a LB with a lead blocker? No problem. We can still run trap and wham and have a lead blocker all the same. The difference is just who is trap blocking the DT.
Let's check out a video of the Lead Wham.
Frontside Influence Traps and Whams
Oh, but you don't just trap and wham people, that would be too simple. Sometimes, you also want to influence the defense by pulling linemen and then actually intending to run behind them. The "influence" here, forces the defense to react to the pulling blocker, which actually takes them away from the play.
Here's the Lead T
Here is your standard influence trap, the defense is forced to react to the Lead T play that often breaks to the outside.
And, of course, you can do the same with a frontside wham block.
But with Power O being the base play, it is often the backside influence play (pulling the backside OG then blocking the DT over the pulling OG). Pull the OG, watch the defense try to get to the point of attack first, only to have the point of attack being the spot they just vacated.
Ah, Hell, Influence Everything
Sometimes you out-think yourself a bit, but for what it's worth, that's a fairly standard man blocked influence wham with a lead block (the TE is trying to lead up in through the hole).
Lead Power O
But why stop at only adding that many more gaps to the point of attack. Why not two FBs and a puller. Yes, Lead Power O.
While Harbaugh will run it (note the small counter step from the RB, that is only to give the blockers time to cross), here is MSU running it against Baylor.
No, it's not just Harbaugh doing this, but that just shows the strength of such a concept.
Michigan will also gap/man block all along the LOS and run a double Iso, with both FBs isolating both ILBs. The key here is that the FBs have to react quicker than the ILB and meet them in the 2nd level, hard, and in charge, before the defense can react and execute. That's a difficult task for the LBs to succeed in doing, especially when it's a sudden change up from all the other games you've been playing.
Spreading the field is great, and has its advantages; as does using in-line TEs and H-backs from a wing position. All force the defense to defend laterally and vertically. But only with FBs can you get this type of run game variety. FBs can be inserted anywhere along the LOS, and by using two of them, you allow yourself to pull OL or not pull OL and still use your entire playbook. This is another wrinkle that I have long loved, I love the use of FBs and H-Backs in this manner, because at the end of the day, it forces the defense to think. And when the defense is thinking and the offense is simply bashing their heads in, the the run game gets-a-rollin', and there isn't much that can stop it.