Welcome Back, 4-3 Under: The Linebackers

Shawn Crable would be ideal for the new regime

Last week I put up a post explaining how Michigan's defense will look in the coming years under new defensive coordinator Greg Mattison.  Today we'll take a look at the linebackers.

STRONGSIDE LINEBACKER (SAM)
Alignment:  9-technique, which is on the outside shoulder of the tight end
Gap responsibility:  D gap, which is outside the tight end
What should he look like?  If you're building a team, this guy should be your best overall athlete with the best combination of size, strength, and speed.  He resides on the strong side of the formation and holds the point of attack on most run plays.  He will be blocked on every running play and take on blocks from fullbacks, tight ends, and pulling guards.  He also needs to cover running backs out of the backfield, drop into flat or hook zones, or occasionally slide inside and blitz the interior line.  These varied responsibilities require unique overall athleticism.  Shawn Crable, who was about 6'5" and 245 lbs. and could run like a deer, would be the prototype.The physical freak you create in NCAA Football who's 6'6", 260 lbs., and runs a 4.3 forty . . . he's a SAM.
Best physical fit:  Jake Ryan (6'3", 224 lbs.).  Keep in mind that Ryan is just a freshman and probably weighs more than 224 at this point, but all these players are coming from a defense that didn't recruit players for the SAM position.

MIDDLE LINEBACKER (MIKE)
Alignment: 3-off, which is on the outside shoulder of the strongside guard and off the line of scrimmage
Gap responsibility:  B gap, which is between the strongside tackle and guard
What should he look like?  Your middle linebacker should be the tackling machine.  As opposed to the middle linebacker in the 3-3-5 (who lines up directly over the center), the MIKE in a 4-3 Under aligns himself on the strong side of the formation.  The formation of the defense funnels most running plays to the MIKE's vicinity.  He often has to defeat blocks from fullbacks, which means he has to have a sturdy frame.  He also needs to have a nose for the ball and roam sideline to sideline.  Unlike the 4-3 Tampa Cover Two defense, though, the MIKE in the 4-3 Under is somewhat protected in the passing game.  He needs to be able to cover crossing routes and hook zones, but the deep middle of the field will be covered by one of the safeties. Obviously, everyone would like to have a great athlete at every position, but the MIKE can afford to be a little stiffer in pass coverage.  The ideal size for a middle linebacker would be about 6'2" and 245 lbs.
Best physical fit:  Isaiah Bell (6'1", 245 lbs.)

WEAKSIDE LINEBACKER (WILL)
Alignment:  1-off, which is on the inside shoulder of the weakside guard and off the line of scrimmage
Gap responsibility:  Flow to the ball
What should he look like?  Michigan had a great deal of success with smaller weakside linebackers when Hoke and Mattison were in Ann Arbor earlier in their careers, and I see no reason why that philosophy would change in the near future.  Guys like Larry Foote and Ian Gold were both very effective while being a shade over 6' tall and 205-225 lbs.  The WILL rarely needs to take on a fullback because of the defense's alignment; with a NT over the center and a DT over the weakside guard, it's difficult to create enough space in that A gap to send a big fullback leading up through the hole.  That means the WILL often gets a chance to flow to the ball and make things happen.  He will blitz often and pick up running backs or slot receivers on rare occasions, so he needs to be somewhat more agile than the MIKE.  So despite technically being an inside linebacker (aligned between the tackles), he can get away with being smaller.
Best physical fit: Antonio Poole (6'1", 210 lbs.)