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Some Clarification is in Order: A Link in the Chain or a Hole in the Net

Both the defense and the offense has aspects of a net or chain, but how do they vary? (Photo by Justin Edmonds/Getty Images)
Both the defense and the offense has aspects of a net or chain, but how do they vary? (Photo by Justin Edmonds/Getty Images)
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As I've studied football and football theory, as I've had the chance to listen and talk with coaches, I've learned a lot, but one idea has stuck with me. I first heard it from Mike Holmgren and then a year later from Tony Dungy and Andy Reid. While two of these men run similar systems (Holmgren and Reid) they do differ greatly from Dungy in most aspects. But something they alluded too, though didn't expand on, is that in football there are chains and nets.

Now we've all heard the saying that a chain is only as strong as the weakest link, this applies to most situations in football as well. At other times, the game of football looks more like a net, having a wide, multi-layer feel to it. Today I want to delve more deeply into these ideas and while this won't be statistic heavy like some of my other articles, I hope it still can educational and get you thinking, which is what the real goal is.

Chains and Nets:

Chains and Links View Point

Football is the ultimate team sport, we've heard this many times, and it holds true (we won't get into this too much though, another discussion all together), and in many cases, teams design formations and plays to eliminate the individual because no matter what you think, the reality is one mistake by just one player can destroy a play. Brian Burke at Advanced NFL Stats called this Single-Point-Failure Model when he discussed the passing game, but I want to expand this to both sides of the ball. As he is speaking about the passing game he says:

Every football play seems like a desperate, chaotic scramble of 22 players. Where baseball is a series system, football is more of a parallel one. In a very simplified way, much of a football play can be modeled as several simultaneous one-on-one match-ups.

This kind of system is similar to a chain. If any one link fails, the entire system fails. No matter how well the other offensive lineman are blocking, if one lineman misses his block there’s probably going to be a sack. And if one pass defender blows his assignment, either by being beat in man-to-man or being in the wrong place in a zone, there’s a good chance for a big pass completion. This is why a football play can be thought of as a "point-failure" system.

Now I don't agree with everything Brian says in this quote, or as he continues his article, but he makes a key point, how football schemes, at their most basic level, are just chains. Let's look at this in a hypothetical system where quarterbacks perfectly execute their jobs, if a receiver is open, they complete the pass, if a wide receiver isn't open, the corner perfectly execute his job and stop the play. As Brian said, if just one offensive lineman misses his block, there is potential for a negative play like a sack or at least the quarterback is pressured into making a play he might not want to. The same can be said for a corner back and wide receiver, if the wide receiver gets past, breaks that link, that play has increased likelihood of success.

Imagine this as a game of red-rover, where two lines of people are sending their men at each others lines to break through, if no wide receiver can break through the defensive "line" before the defense can break through his "line" (well I guess I don't need to put that in quotes) than he's in trouble. The same applies if a wide receiver can break through before a defensive player can, success is likely achieved. Every play in the NFL is designed to break through the weakest link in the chain and the opposing side tries to attack the weakest link while compensating for their own weakest link.

Here's a quick example of an empty backfield offense, let's look at this:


If the defense knows the right tackle is the weakest link on the offensive line and they see this empty backfield, they shift the line and have their best defensive end attack him, say a quick guy like Elvis Dumervil moves to that side, he beats his man, success. Their secondary would be struggling to cover this many wide receivers if they didn't attack this weak link in the offensive chain. Let's look at this from the offenses side:


The quarterback sees the defense is in man coverage and knows the defense is shallow at cornerback. Knowing that he has his best wide receiver outside on the left side, he knows they will likely double cover him, that means they will either use the two corners on that side to cover him or use the free safety to help cover him. That means the inside receiver on that left side has a chance to beat a bad corner. He'll have the chance to exploit this.

It's About More Than Links, It's About Nets

This brings us to point where many of you are thinking, "but it isn't just that simple, in most cases, either on offense or defense, there are more layers" and you'd be right. While the chain methodology of studying football does hold true, it's not that simple. If an offense knows their right tackles is a weak link they will put a tight end on his side or put a back to sit in a block for the play. The same can be said for the defense, actually this is the whole basis for the Cover 2 defense, to place safeties back in coverage behind the corners if they get beat. In the most basic Cover 2, the free safety is meant to be a last resort player to stop the big play.

When looking at chains, it's simple, as Brian says:

So, in a very simple way, a passing play is like two chains under strain. One chain is the pass protection, and the other is the pass defense. Each link is a player vs. player match-up, and it has its own probability of breaking based on the abilities of the respective players. The first chain to break loses.

But layers help strengthen these weaknesses. Take our red-rover game and instead of just one long line, you have layers of lines with each one meant to compensate for the weaknesses of the line in front of it. If an offense is weak on the right side of the line, backs and tight ends are added, just look at the I-Formation being created. If a defense struggles to stop the run in the middle, they add a linebacker or bring a safety up to shore up those weaknesses, the 46 defense is an example of this.

These adjustments create more of a net than a link. These two situations are the basis of all game planning. Do you spread yourself thinner in terms of protection and try to break the other team before your break them or do you add layers of protection to try and ensure success? In a more simple sense you could relate the link/chain to a sword and the net/layers to a shield. Both offense and defense could go with a shield, an I-Formation against a Cover 2 defense. Or they could both go with the sword, an empty backfield offense against a 5-2 defense meant to get after the quarterback.

Most football fans have understood this, it's basic, but it's something we don't really think about. We know that sending an extra blitzer at the quarterback opens up the defense to the run or pass. The same can be said if you keep a tight end in to block you lose a weapon to try and attack the defense.

The Cover 2 was designed to allow aggressive corner play because they know they have safeties back in zone coverage to compensate. The fullback was inserted to either block a pass rushing linebacker or to help pick up a linebacker in the run game. The H-Back was created to act as a tight end to help pick up blitzers by Joe Gibbs. Each formation, both on offense or defense, is designed to either protect a weakness or attack the weakness of the opposing team.

What Does This Mean?

It's actually vital important and could change how you view certain positions value. Let's examine the offensive line, perhaps the most pure chain/link example in the league. Many value the left tackle as one of the top 2 positions in the NFL. But look at some of the best left tackles, or any offensive lineman for that matter, in the league. Now I'll just list a few in no real order:

- Jake Long (Miami)
- Ryan Clady (Denver)
- Jason Peters (Philadelphia)

Notice something? All of these teams surrendered a massive number of pressures or sacks. The reason for this is well explained by Brian:

This is why having a world-class, Hall-of-Fame worthy tackle might not mean that much for a team’s overall pass protection, especially if there are weak blockers elsewhere on the same line. The math works out so that it’s better to have a line full of average blockers rather than a line of one all-pro and four slightly below-average colleagues.

It makes sense, if the defense knows you have a fantastic left tackle and a terrible rest of the line, they will just send all their blitzers to the other side. The same can be said for a top tier guard or center. While having a great center is important for helping direct the offense, if he's a great blocker, they'll attack the line from the outside. Teams that don't surrender pressure and sacks are those who don't really have a weak player, they may not have an All-Pro tackle or center, but they really don't have any weak links. Take a look at the Bills (2nd), Titans (3rd), or Falcons (4th), not big name lineman, but all have no real terrible lineman.

Now that's not to say that we shouldn't seek out top tier lineman, but if the rest of the line is terrible, it's largely wasted. I'd rather just have an average line than one great lineman and four other terrible lineman.

Let's look at this from an offense view point with creating mis-matches. The Patriots and Eagles are two offenses that are masters of this. They scheme their plays to attack the weaknesses of their opponents. Say the Eagles are playing a team with good run stopping linebackers but they struggle in coverage, they run a play action with LeSean McCoy (or Brian Westbrook in the past) to beat the linebackers as a receiver.

The Patriots exploit similar situations with Wes Welker and their tight ends. All three of these players have spent time behind Tom Brady and then when Brady sees a weakness he sends the player out to exploit that weakness.

You also see this with the Ravens using Vonta Leach and Ray Rice, if Flacco sees a pass favorable defense, he can shift Rice out to wide receiver and have Leach pass block instead or run block. Look at the Chiefs with Dexter McCluster and Jamaal Charles. There are examples of this across the league, where teams try to maximize their talent to create mismatches to "break the defenses chain."

That is what makes great defenses great. The Bears defense for example is built to stop this by having players like Brian Urlacher who can do everything well. They have talented enough corners and safeties that mismatches rarely happen. The Texans and Browns are similarly built to not have mismatches. Other teams don't mind mis-matches because they are so strong in other areas, the Steelers and Ravens are examples of this. Their front seven are so good they compensate for weaknesses in their secondary.

Let's look at this from the stand point of the Broncos, we have a top tier corner in Champ Bailey but as we saw the last couple seasons, if the safeties are weak or we have a weak #2 or nickel corner, offenses will just exploit them instead of picking on Champ. The Raiders saw this with Nnamdi Asomugha, while he is a top corner, the Raiders pass defense was weak because their other corners struggled.

Wrapping Up

Now I'm not sure a good way to measure this perfectly, and I really don't care to study that at this time. This was more a thought experiment to get our minds going. So let me know what you think, and I hope this was educational and helped you better understand some of thinking behind why coaches and quarterbacks do what they do when they gameplan.