Even though they make up 45% of the offensive players on the field at any given time, and even though any coach with half a brain will tell you that "games are won and lost up front," I've noticed that many fans and coaches who weren't former offensive linemen are often confused when they hear the terms "man blocking" and "zone blocking" scheme thrown around. They wonder "what do these terms even mean?"
The confusion has gotten so bad that I've seen fans get upset when they read online that their team has hired a particular offensive coordinator or offensive line coach who stresses "zone blocking" because they think it's some newfangled thing he pulled out of his butt at his last stop and that the zone is why their offensive line sucked.
Well... no. Man blocking schemes are old school, going back to the prehistoric origins of football, even back before the days of Pop Warner and the Single Wing. However, Zone blocking isn't all that new either. It's been a staple of every NFL running game since the mid 90s, and has been the choice of just about every dominant NFL rushing team since at least the mid 80s. Now it's become the foundation of ALL NFL teams' running games. In the NFL, zone blocking is the way to go because their pro offensive linemen are athletic enough to pull it off and because it gives them more time to work on protecting their $100 million QBs.
So why do so many people still have no clue what it is?
I blame announcers and a tendency to try and oversimplify things. When many coaches to try explain the difference, they'll say "Man blocking means the offensive lineman has to block a person, while Zone blocking means he blocks an 'area.'" From that definition it sounds like they'd always have the playside tackle always blocking down on a 1 tech DT in a man scheme or they tell him to block some very specific patch of grass which may have no one on it...
So, let's examine these concepts, shall we?
First off, making the debate "Zone vs. Man" a bit misleading. There's also "Gap" Blocking, which splits the difference, when these terms are applied to the running game. Man vs. Zone in pass protection is a little different.
"Man blocking" does mean that the offensive lineman is assigned a particular defensive player to block-- the specific blocking assignment is built into the play. But it's not always as specific s "block the NG" because there might not even be a NG.
Man blocking systems basically require a different set of blocking rules for each play. Because defensive fronts vary so much, a lot of Man blocking teams will use a numbering system with their blocking rules. The 1st man on the playside (i.e., the side of the field the ball is being run to--the center and anyone lined up over him is always the first man on "the playside") is labeled "0." The second will be "1." Third is "2." Etc. The blocking calls may depend a great deal on the Center identifying the front as belonging to a particular "family" and calling it out to the rest of the OL, who then picks their man and goes to work. As you may have figured out, all of this can get complicated and confusing, so Man blocking rules aren't very popular in the running game these days.
Zone blocking assigns the offensive lineman an "area," as people say, and gives them general rules for blocking it. If you look at zone blocking, what it really does is take old school Man blocking schemes and boils them down to the underlying principles that make them work against different fronts, then teaches the principles to the offensive linemen so they can (theoretically) figure out their own answers to whatever a defense throws at them on the field.
There are basically only two types of zone run blocking: Inside Zone (IZ) and Outside Zone (OZ). On IZ, the offensive line looks to open a hole off the playside guard, while in OZ the aiming point is off the playside tackle/TE. OZ zone blocking can be as simple as "everyone reach block the playside gap." If the rules dictate that two offensive linemen block the same defensive lineman, you'll get natural "combo" blocks where one player base blocks the defensive lineman, while the other helps him for a couple of steps and then slips off to block a pursuing LB.
Zone blocking seeks to establish "a massive wall of blockers moving to the playside." It's often further augmented by cut blocks on the backside and by giving the ball carrier a "read" to make. The ball carrier will key a particular defender (such as the NG) or maybe a particular blocker (such as the OT's butt). Depending upon where the NG winds up going, the ball carrier will attack the furthest playside gap or run through a predicted cutback lane. To make the most of this, it requires a runner with great vision and good agility. Terrell Davis and Emmett Smith both made their livings off the zone cutbacks during their careers, like the one Davis makes when he cuts off the Tackle's block on an Outside Zone play in the example below:
Nowadays shotgun spread teams will further augment their zone running games by having the QB read an unblocked defender on the backside of the zone and keep the ball around that edge if a better hole opens up there. That's the Zone Read, in a nutshell.
Many zone blocking teams make it a point of emphasis that they only have a handful of blocking schemes in their playbook, total, though they may run 4 or 5 different plays off each. Their reason for doing this is to keep it as simple as possible for the offensive line because one missed block can destroy a play and defenses will incorporate all sorts of shifting and stemming into different fronts to try to make that happen.
However, while Zone blocking may sound like the obvious best choice, there are some caveats to using it. First off, your linemen still have to know what they're doing. A confused offensive lineman, even in a simple scheme, is still an ineffective offensive lineman.
Second, many coaches will tell you that a Zone blocking offensive lineman must have some athletic ability, as zone footwork can involve intricate "bucket steps" and blocking very athletic defensive players on the move.
Third, because of the use of things like bucket steps (where the offensive lineman will quickly take a couple of steps back or horizontally to get his body in better position before he really gets into his block), many coaches feel that zone blocking rules must be adjusted or replaced in short yardage situations, otherwise their linemen will get blown up at the line.
So that's it, right? You man it or you zone it and you run the ball. Great!
Ah, but as Lee Corso would say: "Not so fast, my friend!"
As I said earlier, there is a third option, Gap blocking and it splits the difference. Gap blocking is what you'll see a lot from Wing-T teams and other offenses that like to pull and trap with their linemen. A gap blocking scheme is basically what it sounds like: a player will block the defender in the specific gap on either side of him.
The simplest explanation of this would be the blocking on Power, where you want the DE to be kicked out. In the blocking on that play, every offensive lineman on the playside will block down (block the defensive lineman or linebacker in the playside gap inside of him). The backside guard will pull and either kick out the DE or lead through the hole, while the backside OT will cut block any defender in the backside B gap. It's a simple scheme, but you don't get many opportunities for double teams unless you want to tweak it by calling one (like having the playside G and T combo any DT in the B gap).
Feel the Power!
While gap blocking schemes are simple, they still require that the offensive linemen memorize and apply a particular set of blocking rules for each play. Gap blocking schemes also require that the runners follow an assigned track and wait for the hole to open up. If the hole doesn't open as it's supposed to, the plays usually aren't very successful.
So that's the running game. Now for "Man" vs. "Zone" in the passing game.
This is a little simpler. Basically, a "Man" pass protection scheme is the classic "Big on Big" (BOB) blocking. The offensive linemen will block the defensive linemen across from them, an uncovered linemen will read the nearest LB (or LBs) and the backs will take care of any LBs or DBs who try to blitz. They may also be assigned to help with a double team on a particularly tough pass rusher. There are other versions, too (like having an OL block a specified LB while a RB takes a DE), but classic BOB is the most common one used.
It's usually good, sound protection, but with modern zone blitzes and stuff a Man protection may struggle when a defender occupies an OL just by faking a pass rush, then drops off while someone else rushes through the hole behind that OL. A good example of this came in the Superbowl a few years ago when the Giants took advantage of the "Double Reads" that the Patriots' man protection schemes asked of the Centers and Guards by using zone blitzes. It wasn't that the Patriots' line couldn't block, it's that they were obeying their rules and getting suckered into trying to block the wrong guys.
Zone pass protection is sort of like a "Gap" version of pass pro: each offensive linemen will step into the gap on one side of him and block whatever comes through there. If no one attacks the gap, he'll keep an eye on the men next to him and combo with them, but he still must hold down his primary gap responsibility through the whole play. A simple type of Zone Pass Pro is the "Step In" protection that you'll see in a lot of 2 back offenses: the offensive linemen each step into their inside gap and block, while the RBs and TEs will take whatever comes around the outside through C/D gaps.
The problem with zone protections is that you might sometimes wind up with situations where the blocker with the outside gap gets isolated in a 2 on 1 situation with a blitz, and you have a greater risk of sometimes getting unfavorable match-ups where a RB has to block a DE or even a DT by himself.
In pass pro, you'll see a lot of hybrids of Man and Zone blocking. It's common to see a team zone one side, while they man the other with hinge blocking, etc.