Danno

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So, what exactly is a ZBS? It’s actually exactly what it sounds like. Think defensive coverages. Where man (or "power") blocking is simply finding your assignment and taking him out of the play, a ZBS calls on its offensive linemen to cover an area and eliminate players coming into that area. The ZBS slightly abandons size and strength in lieu of quickness and lateral movement. There is more technique and deception involved in a ZBS.

For starters, double teams are actually favorable in ZBS. The backside defensive end (or the "jack" in most 3-4 schemes) is left to run free into the backfield, while the line slides towards the side they’re rushing. A player may also perform a "reach block" in which he steps 45 degrees at the snap before attempting to step inside of a defender’s leg and engaging him. This is also called a "shield block," since it eliminates a defender’s ability to read the play.

Ingram, of course, hails from Alabama, who famously run the best ZBS in the country. Other running backs out of ‘Bama include Eddie Lacy of Green Bay and, infamously, Trent Richardson, drafted in the first round by Cleveland before being traded for a first round pick to Indianapolis. Green Bay runs a ZBS, Cleveland and Indianapolis don’t. The comparative success of Lacy and Richardson should speak for itself in terms of which works better for Alabama products.

To know if it’s man or zone blocking at the snap, watch the first step. If their hips immediately open to the strong side, it will be ZBS. If their first step is down the field to engage someone, it’s man to man.

Asking a running back to switch to running in a man scheme from a zone one is like asking Rob Ryan to coach the offense for a season. It requires an entirely different skill set for an RB to run through a line that is creating holes through physicality rather than through coordination. This is where Ingram suffered. It’s admirable that Payton has taken such large strides to benefit his player’s strengths, especially since the transition from man blocking to zone is relatively easy for an offensive lineman.

Rest of a really really good article from CanalStreetChronicles...
Conversion From Man to Zone Blocking Benefits Mark Ingram, New Orleans Saints Offense - Canal Street Chronicles