I get quite a bit of reader mail from MHR members, members from around SBN's football sites, and sometimes someone who has linked to us from an outside source (such as Sports Illustrated).  I recently received this question, and since it is topical to the current Denver defense, thought I would post it instead of just sending back a reply in the e-mail.

Any chance that you could do an article/ post at MHR on safety play. I feel like I am getting more knowledgable all the time, but I am confused as to the scheme the Broncos are using, and how the way we are using our safeties is detrimentally effecting the strengths of players like Champ and Dre.
 
I would be stoked to know this, and also if Barrett has the skill set that would allow us to go back and play to Dre and Champ's strengths.

Ben Boyd

You've got it Ben!  Let's take a look at how use of safeties affect corners in a defense.

First, let's define the safety position.  While safeties vary in types, assignments, and uses, their primary job is to stop the big play.  They are primarily "goalies" in the hockey sense.

The free safety (FS) is often lined up on the weakside, and almost always plays a deep zone and plays his own assignment based on what he is seeing develop (we call this a "true free safety"). 

The strong safety (SS) lines up on the strong side, and is often the "lesser" safety, though no less important.  A majority of his time is spent in deep zone, but he can also be used to cover a receiving TE.  Teams prefer to use a SAM linebacker to cover TEs to keep their safeties covering the deep field, but if a team has a slower, run blocking SAM, or if the TE is particulalry fast, the SS gets the assignment.  Because SSs are usually a little bigger (but not as fast), they have developed reputations as being the heavy hitters.

For a quick read on the difference between 2 deep safeties (the most common alignment for safeties), and the term "cover two", which has nothing to do with our discussion, read here.

Now onto Ben's question.

In Denver's '08 defense so far, the team has experienced issues with stopping run plays.  This is a problem that came over from the '07 season, when Denver chucked a few of their better linemen and brought in free agents to play a Contain System.  Now, stuck with a defensive line in transition away from the contain (Denver chucked the Contain players too), and also saddled with key injuries (including Denver's rookie DT pick), Denver faces a crisis in run prevention.

As early as last year Denver tried to fix the problem by dropping a safety into the box (playing a SS as a kind of fourth LB).  Two things happened right away, and both go to the heart of Ben's question.

1. Champ Bailey looked human.  All of a sudden he wasn't getting as many interceptions as he used to.  Even though most QBs avoided throwing to him, some of the passes turned into big pass plays.  (Most fans will recall the Green Bay Monday Night Debacle, where Bailey looked like he fell for a slant pass of a go route.  The fault was really at safety).
2. Bly, who is second only to Champ Bailey in interceptions going all the way back to 2001, looked human too.  More passes went his way (because Bailey was on the other side), and many Broncos fans still persist in thinking that Bly is a bust.  The truth is, his production dropped when Bailey's did.

Need more evidence?  In recent games Bly has looked much better, and the common variable is that we have moved the SS out of the box.  (Bailey should look better on his return too.  He is currently injured).

So we see a pattern that shows two deep safeties make a difference.  But the question is, "Why?"

The key is understanding "over" and "under" coverages.  When a defensive back (a corner or safety) is between the QB and the receiver, he is said to be "underneath".  This term comes about because, on a chalk board with Xs and Os where plays are diagramed, the defender is shown underneath (below) the receiver.  Conversly, a DB playing "over" is chalked in on above, or "over" the receiver (between the receiver and the endzone).

Playing "over" gives you less of a chance of a big play for the offense, and a better chance to tackle.  Playing "under" is high risk/high reward because you are in a great position to knock down or INT the ball, but in a poor position to tackle if the receiver gets the ball.

Another key is understanding how corners line up.  From an earlier MHR University post:

There are three (main) types of line ups.  Terms vary, so I'll use the terms we used in our program.  The line up goes far in determining the way the CB will cover the play.  Each has advantages and disadvantages.

• Tight
• On
• Off

"Tight" coverage features the CB as close to the WR as the line of scrimmage allows.  It typicaly signals that the CB will "Bump and Run" the WR.  This means the CB will "jack" or hit the WR when the WR starts to move, then cover him closely when he recovers.  The advantage to this alignment is that timed offensive plays get disrupted.  It also slows a WR who is faster than his coverage.  The disadvatages are that the CB will get locked up in a run block if the play is a run, and if the bump is not well executed the WR will leave the CB in his dust.

"On" coverage features the CB a yard or two behind scrimmage.  This allows him time to react to pass or run, but keeps him close enough to cover his assignment.  Many zone CBs line up this way (relying on SAFs for deeper coverage), and this is the most common line-up for man coverage as well.

"Off" coverage is an interesting way to go.  The CB lines up far back from the line of scrimmage, perhaps ten yards "off".  In most cases it signals that the CB is willing to give up short passes, but doesn't want the WR to get away from him.  Big mismatches favoring speed for the WR will get this line up.  It is playing very cautiously, so as not to give up the big play.  Oddly, the best CB in the NFL (Champ) prefers to line up this way.  Most elite CBs do not.

Champ has such blazing speed (and the ability to seemingly defy physics by turning on his hips without slowing) that he can afford to read the QB and the WR from a distance, and still fire in for the hit/INT on short passes.  He covers the distance in almost no time, and uses off coverage to buy a second to determine his commitment on the play.  In longer plays Champ just uses his speed to stay on his target.

Now that we have our terms straight, let's see how two safeties are critical to effective CB play.

Both Bailey and Bly are skilled "underneath" receivers.  Even though Bailey likes to line up "off" his principal (his target / his assignment), his goal is to dart in for the INT or the bat-down every time.  Neither Bailey nor Bly like to time hits with an incoming pass; they want the big play.  In Bly's case, his reputation as a "gambler" is based on the idea that he likes to line up "on" his receiver and play underneath.

Have you noticed the complaints from Denver fans at MHR that we are only rushing three players, and playing our CBs in off coverage?  Well, it goes back to the fact that we are missing a SS (who is in the box).  With the safety missing, the FS has to try to cover the entire defensive backfield by himself.  To compensate, Denver's defensive coordinator is forced to play cautiously.  He plays both CBs in off coverage (not Bly's style), and wants them playing "over" their principal. 

While Bailey is comfortable playing "off", he is not a natural "over coverage" player.  He will still make most of his tackles, but his INTs will plummet.  Notice the emphasis on "most".  When he misses, there is no longer a safety on his side to cover up the miss, making Champ look bad. 

Bly, on the other hand, has an even tougher road.  Bly is not only being forced to play "over", but "off" as well.  Even when he played in Detroit, he was playing "tight" and "under" and was awfuly good at it.  But in Detroit, he had a safety behind him everytime.

Now, whenever Bailey and Bly want to do their thing (play the position the way they were built to play it), they have an extra distraction.  "Can I jump this route and knock down the ball or get an INT, or do I have to sit back and let the WR make a play on the ball and then try for a well timed tackle?  Well, let's see.  First I have to see where the safety is."

Is it starting to make sense?

Here are some examples from the same MHR-U article I quoted earlier:

CBs and the relationship with other positions

CBs rely on the front seven to hurry the QB into making mistakes.  A good pass rush makes the QB get rid of the ball faster, and makes the job of the CB easier.  Most folks know that.

What a lot of people don't know about is the relationship between CBs and safeties.  Who do you blame when a QB gets sacked?  You can blame the OL for not protecting him, or you can blame the QB for holding the ball too long, or you can blame the WRs for not getting open.  But a lot of folks don't realize that a blown play by a CB may actualy be the fault of the SAF(s).

CBs make a lot of decisions based on "situational awareness".  In other words, the CB must know where his SAFs are before deciding to go for an INT, or to commit to an expected route.  Bly may go for an INT, expecting the FS to read the play correctly and to come over to the weakside.  But if a slot receiver made the FS bite to the center of the field, Bly may not have the help he was supposed to have.

In another example, Bailey may get caught in a crossing pattern.  He commits to a streak because he sees the QB setting his feet for a pass and notices both WRs racing for the endzone.  He also expects the only safety not in the box to keep his zone in the center of the field.  But if the SAF "bites", and commits to Bailey's man (instead of keeping the center of the field), and Bailey's man cuts in for the slant, the blown play looks like Bailey screwed up.

I hope that answers Ben's question.  A SS in the box may or may not help the run game, but it certainly helps to wreck a pass defense.  The natural look for a base formation will include 2 safeties.  Add one, and you are in a heavily skewed pass defense.  Take one away, and you have either a 4-4 or a 46 defense and little to no protection against the pass.

The 4-4 is weak against the pass for the above reasons.  (Unless you are facing only one receiver, in which case you use two SAFs and one CB.  This is common at the HS level).  The 46 is likewise geared towards stopping the run, but is very rare at the pro level.  (The Eagles have got by because of a freak of nature name Brian Dawkins playing at FS, and because the scheme places extreme pressure on opposing QBs).

Last, the Josh Barrett question.  If Barrett is used with another safety in the deep zone, I think he posses the speed and skill set to develop into a heck of a safety.  I hope we get to see enough of him to determine if we really should take or pass on a safety in the '09 draft.  Because we have wasted so many games with only one deep safety (which makes them all look bad, leading to firings), we really have no idea of what we have back there.