Check out my video breakdown of the 49ers’ new defensive alignment.

Here are the Cliff’s Notes:

STRENGTHS

1. Rushing the quarterback. The Wide 9 makes a speed rusher even more dangerous, because he lines up outside the tight end. The offensive tackle has to kick slide quickly and cover lots of ground just to get his hands on the Wide 9 defensive end (think Dee Ford). By forcing the offensive tackle to move so far, the Wide 9 creates space inside for the 3-technique defensive tackle (think DeForest Buckner) to rush one-on-one against a guard. The 49ers have struggled to create one-on-one matchups for Buckner the past three seasons.

2. Defending finesse runs outside the tackles. It’s extremely difficult to run outside outside zone or jet sweeps against the Wide 9, because the  defensive end is not attached to the tight end. If the defensive end fires straight upfield after the snap, he’s on the tight end’s outside shoulder already, forcing the outside-zone run to break inside the tight end. The Wide 9 sets the edge. He is the D-gap defender (the gap farthest from the center). Last season, the 49ers’ strong-side defensive end was head up on the tight end, meaning he was the C-gap defender. This alignment allowed the strong-side linebacker to defend the D-Gap and be a smaller player, because he had to chase down people near the sideline rather than fill gaps between the tackles.

3. Playing Cover 2 and 2-man. The three linebackers are bunched together between the tackles. They’re all in perfect position to play their zones in Cover 2.

WEAKNESSES

1. Playing Cover 3. The curl/flat defenders (strong safety and strong-side linebacker) are farther away from their landmarks pre-snap in a Wide 9 alignment compared to the traditional Seattle defense. The strong-side linebacker is in the box, so he has an extra few yards to run to get to the flat. And the strong safety is 10-12 yards off the line of scrimmage, so he has a mile and a half to run to get to the flat. This means teams will attack the 49ers’ defense in the flats next season. In practice, the 49ers have been dropping the strong safety into the hook zone over the middle and sending both outside linebackers to the flats.

2. Defending runs between the tackles. It’s tough for offenses to break the outside contain of a Wide 9 defense, so they must attack where the softness of the defense is, and that’s inside. By spreading out the defensive linemen, the defense has created cavities offenses will try to expose by making their run game more direct. The 49ers’ small linebackers better wear big-boy pads next season, because offenses will be running between the tackles. They’ll run inside zone plays, and pin-and-pull concepts such as G-Leads, Whams, Traps and Power plays. The strong-side linebacker (Dre Greenlaw?) has to be a stud, because he’s playing the C-gap between the tackle and tight end. Offenses can block the Sam linebacker with a tight end, block down on the 3-technique with the offensive tackle and pull the play-side guard to kick out the Wide 9 DE. That’s a G-Lead. The Wide 9 alignment makes it easier for offenses to isolate the 3-technique (Buckner) in the run game, and exposes him to situations where he’ll have to play the down block from the offensive tackle more often.

3. Defending play action. The Sam linebacker must explode downhill toward the line of scrimmage whenever he sees run action coming toward the C-gap, so he’s easily fooled by play action. He will bite every time a quarterback fakes a hand off. Last season, the 49ers’ Sam linebacker and strong safety both lined up outside the tackles, so they didn’t have to overreact to run actions, and they both had clear views of the run fake, because they were outside the tackles and didn’t have to peer through bodies to find the football.

Do you like the Wide 9 alignment? Do you think it will improve the 49ers defense? Or should the 49ers have stuck with what they used the past two seasons? Why or why not?