Summer School: Learning About LBs in the New 4-3 Defense

By: Mike Messner (@teachermike72)img_1386

Final Edit: (@Zachhernan)

School’s out, Niner Fans!  (Except it’s not.)

Not long ago, I was talking to Zach Hernandez, my editor and friend, about the 49ers linebacker corps.  I told him there needed to be something on 49ersHive about the different types of linebackers, now that the team has shifted to a 4-3 base defense.  There’s too much jargon, I told Zach.  Someone should sort it out for the readers.

Well, I thought I’d take a stab at it.  Here come the disclaimers!

In getting ready for this piece, I consulted a number of different resources, to whom I will give attribution to at the end — inasmuch as I never played the game in high school or college, I thought I should get as much background as I could on the terms and their roles.  Anything that ends up getting posted on the blog that is incorrect, blame me first and Zach second.

You should also know now that I am not going to address the pass rusher, or LEO role, that Robert Saleh is introducing.  This is going to be a discussion and clarification of the meaning of the three linebacker roles in the 4-3, as well as some speculations on who might be on the depth chart in those roles this season.

In the 4-3 defense, you have 11 men on the field playing defense, just as you would have had in the 3-4.  Difference here is that you have four “down linemen,” or in other terms, big-ass guys who are there to keep the offensive tackles, guards and center from opening running room for running backs.   In previous years, the 49ers have used three such men, and although that’s not the only reason they couldn’t stop the run last year, it certainly didn’t help.  So now, the team will have a fourth body trying to maul the other team at the line of scrimmage.

The defense will also generally have two cornerbacks to try to pick off passes, and two safeties to stop any plays that get way downfield from the defensive line.  That leaves three men to work the rest of the defense.  Here are their titles and their duties.

“Mike” Linebacker:


  A Mike tends to be the leader of the defense, by virtue of his athleticism (e.g., he’s gotta be big, strong, and fast) and his intelligence (e.g., he’s gotta be perceptive about what’s going on during a play).  He plays in the middle of the defensive backfield.  More often than not, a Mike is there to stop runs through the middle of the line, though he will sometimes double as a pass defender for mid-range throws if an offense has a large number of receivers during any one formation.

Players who can’t tackle effectively will not be considered for the role of Mikes, since a lot of what they are supposed to do is to stop a charging halfback.

NaVorro Bowman, whom most observers consider the spiritual leader of the team, not just the defense, is a shoo-in for the Mike position.  My guess is that he will be backed up by Brock Coyle and/or Donavin Newsom.

 “Sam” Linebackers:


Sams play on what is called the “strong side” of the defense, across from the tight end — it’s called that because the strong side of the offense has more men on that side of the center than the other.  A Sam will do quite a bit of blitzing when the quarterback is dropping back for passes, but he also has to have the size and the muscle to take on blockers and stop a run play, especially on end runs.  As if that wasn’t enough, a Sam also has to cover the tight end across from who he was lined up in the first place.

So, if you don’t have a bevy of skills, and the ability to call on each one of them at the drop of a hat, you won’t be a good Sam.

If Ahmad Brooks is retained this year, he seems likely to play the Sam role.  If not, the 49ers have Eli Harold, Dekoda Watson, and Jimmie Gilbert waiting in the wings.

 “Will” Linebackers:


Wills are sort of the opposite of the Sams — they play on the “weak side,” the side of the offense that doesn’t have a tight end.  A Will has a lot more freedom to blitz than a Sam, but he also has to do more coverage of passing targets, either out of the backfield or in screen pass situations.  At times, you’ll see a Will be switched to a safety position because of his coverage talent.

Can’t get by a fullback or a tackle?  Can’t jump over a matchbox?  Forget being a Will.

I’m blown away by Reuben Foster’s ferocity and his style, but I also think he needs to be groomed a little before he sees long-term playing time (we ain’t in ‘Bama anymore).  Plus, his shoulder is one that the team cannot afford to gamble with until he refines his tackling. For the sake of experience, I’ll go with Malcolm Smith in the starting role,  backed up by Foster and Ray-Ray Armstrong.

I would like to thank Brian Peacock of Pro Football Focus, my former students Sean Diamond & Christian Dzambic, and my brother-in-law Mark Potter, for their expertise.


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