Welcome Back, 4-3 Under: The Defensive Backs

Welcome Back, 4-3 Under: The Defensive Backs

April 21, 2011
Would Ed Reed be too much to ask for?
(Hint: Not if you’re Auburn.)

In the last week, I’ve broken down the ideal qualities of defensive linemen and linebackers.  Now for the defensive backs:

Alignment:  Dependent on coverage
Gap responsibility:  Outside contain
What should he look like?  Cornerbacks come in different shapes and sizes, but one thing to keep in mind with the 4-3 Under defense is that these corners are going to be put on an island a lot.  This is no longer a bend-but-then-break defense that utilizes soft zones and eschews man coverage.  These cornerbacks need to be up in the receivers’ faces, often playing press man coverage.  Just like any defense, the strongside corner should be a little more adept at tackling and supporting the run.  The weakside corner should have excellent speed and ball skills.  Their job will typically be to force the receiver toward the sideline, maintaining inside leverage and forcing the quarterback to thread a ball between the defender and the sideline.
Best physical fits:  Troy Woolfolk (strongside; 6’0″, 195 lbs.), Courtney Avery (weakside; 5’11”, 167 lbs.)

Alignment:  Strong side of formation, but dependent on coverage
Gap responsibility:  Clean-up
What should he look like?  The strong safety is typically the bigger, more physical player of the two safeties.  He needs to be able to cover a wide range of athletes, from tight ends to wide receivers.  When it comes to run “fits,” he’s typically the clean-up man.  The free safety has responsibility for the weakside A gap, but the strong safety has no such commitment.  That means he should be the most reliable tackler of the defensive back group.  If anyone gets past the front seven, the strong safety should be fast enough to chase him down and strong enough to halt his progress.
Best physical fit:  Carvin Johnson (6’0″, 195 lbs.)

Alignment:  Weak side of formation, but dependent on coverage
Gap responsibility:  A gap or filling the alley
What should he look like?  Because of the unique way the 4-3 Under uses the free safety, this position is somewhat different from what many would expect.  He is heavily involved in supporting the run, and while he won’t have to take on many punishing blockers, he does need to stick his nose up where it doesn’t seem to belong.  He should have good ball skills and the ability to patrol the middle of the field, because he will often be the deep man in Cover 3 or Man Free coverages.  He doesn’t need to be the world’s best athlete, but he does have to be a very disciplined, fundamental player.
Best physical fit:  Marvin Robinson (6’1″, 200 lbs.)


  1. Comments: 21383
    Apr 21, 2011 at 2:53 PM

    I've never thought that the side of the field or the O's formation mattered to which side of the field a D generally put one CB v. the other CB. I thought it was more random or personal preference (i.e., one guy just plays better on the left side of the field). Or, you just put your best CB on the best WR. Thanks for revealing more of the strategy behind this decision.
    So, does a typical offense–when confronted with a 4-3 Under defense–make it's offensive WR alignment similarly? IOW, If I'm a pro-set offense coordinater (i.e., using FB and 2 SEs on opposite sides of the field), then do put Braylon Edwards on a particular side and my non-Braylon WR on the other side? If so, what side (e.g., strongside/weakside) and why?
    This is fascinating and confusing at the same time. I appreciate your insights as it makes the game so much more enjoyable for the casual, albeit nut, fan.

  2. Comments: 21383
    Apr 21, 2011 at 3:13 PM

    @ TriFloyd 10:53 a.m.

    Different coordinators do it in different ways. For example, I believe the Tampa Bay Buccaneers have a left cornerback and a right cornerback. Some teams have a boundary corner (short side of the field) and a field corner (wide side). Still others have a strong side corner (to the TE's side) and a weak side corner.

    Of course, there are some cornerbacks who just play the offense's best WR, and the other cornerback goes to the opposite side.

    A typical offense is going to run its offensive system, regardless of what the defense does. You can't necessarily change your offensive scheme every week without confusing your own players and reducing its efficiency.

    A quick terminology point:

    Split end (SE) refers to the WR that's on the line of scrimmage and away from the TE.

    Flanker (FL) refers to the WR that's typically off the line of scrimmage and on the same side as the TE.

    Some teams do it differently, but generally your FL is the better blocker because he's on the strong side. Conversely, the SE is your more dynamic wideout, a guy who can stretch the field and play a little bit better in open spaces. But this largely depends on your offensive philosophy, how much you run the ball, your use of play action, etc., so it's not exactly set in stone.

  3. Comments: 21383
    Apr 21, 2011 at 3:54 PM

    Hey Magnus. Where would you see someone with Kovacs's skills on an ideal team? Second-string strong safety? You describe WILL as a position that can feature a relatively smaller guy whose job is "see ballcarrier, make tackle," which might be suited to him. Or is 200 lb. just altogether too small for that spot?

    Largely theoretical anyhow I guess given depth concerns at safety.

  4. Comments: 21383
    Apr 21, 2011 at 4:59 PM

    "should have good ball skills and the ability to patrol the middle of the field… doesn't need to be the world's best athlete, but he does have to be a very disciplined, fundamental player."

    So, despite not-great speed, doesn't Carvin Johnson sound like a pretty ideal fit for the FS position? You had expressed doubts before, but I'm (irrationally) optimistic about Johnson at that position. His ability to play as a freshman, despite Grade A athleticism, indicates he has a good head on his shoulders and presumably good awareness.

    From your description, it also seems like Kovacs would be better at FS than SS.

    As for SS…And long-term, given their status as big, fast, semi-LB athletes, aren't Furman and Robinson potentially ideal fits? (assuming they can get the reliable tackling part down)

    Good stuff again.


  5. Comments: 21383
    Apr 22, 2011 at 12:34 PM

    @ BML 11:54 a.m.

    Yeah, I think Kovacs would be a backup SS in an ideal world. But with the talent/experience we have in the backfield, he might be our FS in the fall (which he was in the spring game).

  6. Comments: 21383
    Apr 22, 2011 at 12:37 PM

    @ Lankownia 12:59 p.m.

    Well, it seems that Carvin Johnson is our best safety, period. He would probably be the best fit at both FS and SS. Unfortunately, cloning isn't legal.

    Yes, Kovacs could play FS, and did so in the spring game. I'm wary of having him back there, but his positioning/awareness are clearly better than Robinson's at this point.

    Long-term, I think Furman should be a WILL. I'd like to see more of Robinson. Coming out of high school, I thought he would have the ball skills to play FS. I wasn't impressed in the spring game, and I think a move to SS might be in order, but the jury's still out on that one.

    Thanks for the compliment.

  7. Comments: 21383
    Apr 22, 2011 at 12:52 PM

    @ BML 11:54 a.m.

    I forget to answer this earlier, but I think Kovacs is probably a little too small to play WILL. Plus the WILL needs to be a good blitzer, and I'm not sure if Kovacs could do that well with any regularity.

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