As the 49ers move to a base wide 9 look, a lot of the talk has been about the two DEs, how they are aligned wider, and have more space to work the OTs when pass rushing. But by doing this, the interior of the DL is also further spread apart, weakening the interior run defense.
A front four aligning in a wide 9 is more similar to an Over front than it is an Under front. In an Over front and a wide 9, the 3tech aligns to the strongside. Because the DEs are wider, and the 3t stays in the same position, there is no longer a 1tech. Instead there is a 2i to help alleviate the bubble gaps. These cut ups are focused on the 2i and the different ways the offense can attack him.
This is a 4-3 Over front. Notice how it is similar to when the 4 DL is in a wide 9 with the 3t on the strongside of the offensive formation. Notice the position of the nose tackle, playing 1t.
The post linked below (thanks, NC) contains some input from a former player that played under Jim Schwartz, inventor of the wide 9. I'm pasting some excerpts from his tweets.
https://www.49erswebzone.com/forum/niners/188062-defensive-coordinator-robert-saleh/page732/#post10967
"So another really important position is the 2tech (playing either head up on the guard or shaded inside). In all actuality, the 2tech needs the be the most explosive interior player, the 3tech needs to have a little more balance & control."
"Playing a 1T puts alot of stress on the LB that may have the b gap, because there is ALOT of distance between the 1t and the 5t (defensive end). Playing the 2T (or 2i) helps balance out the integrity of the defense"
In a wide 9, if the nose tackle were to play a 1t, there would be a gigantic bubble gap between the 1t and the weakside DE. To help mitigate this large bubble gap, they move the nose tackle to 2i. While the difference is a couple feet at most, in this close of quarters, the difference is magnified. All these cut ups are of a Jim Schwartz defense.
The 2i is an 'A' gap player and that is all he is. If he doesn't fire off the ball quickly, he is a liability and can get sealed out of his gap.
2i is slow at the snap and the Center is able to cross his face.
2i is now sealed off and is no longer in his run fit.
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Along the front 4, the largest bubble gap is the weakside B gap. A primary task for the 2i is taking on combo blocks from the guard and center. The better he can do this, the more space and time he allows the WILL to diagnose and fill this B gap. Most wide 9 DLs will face a lot of inside zone concepts.
The 2i always wants to threaten the A gap forcing the guard and/or center to maintain the combo block. If he cannot threaten the A gap effectively and command attention from both the guard and center, then one of those two will be able to move to the second level and pick off a LB.
Below, the 2i doesn't hold the combo block and the guard moves to the second level to pick off the MIKE.
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Inside zone again. Notice where the 2i is lined up compared to the play above. Here, he's more of a true 2i. In the play above, it seems like he got lazy and lined up between a 2i and 1t. Small difference in actual distance, but could make a large difference.
2i tries to split the guard and center, and by doing this well, he is able to hold both of them and keep the MIKE clean. Backside unblocked DE must run parallel to the line and chase the play down if there is any hesitation from the RB. No daylight to run in the B gap - there will be hesitation from the RB.
The 2i must also be able to go lateral and run with the center and guard while not giving up ground. (The LT gets defeated, but even if he hadn't, this play is dead in the water due to the 2i and backside DE)
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Because a 2i is aligned further away from the Center when compared to a 1t, this creates a better angle for the Center to downblock on the 2i allowing the guard to pull. I saw some teams attack the 2i like this often throughout a game.
Center downblocks, guard pulls to apply the trap block on the 3t.
This is Kyle's offense.
This play illustrates a couple things that a wide 9 will face - the 2i getting pinned, and the 3t getting trapped. There are times when the pulling guard will lead through the hole instead of trapping the 3t. All one gapping fronts are susceptible to trap blocks since DL are trying to penetrate, but in a wide 9 where interior gaps are larger, interior running lanes are larger.
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Because the 2i is closer to the QB than a 3t, the 2i isn't going to face trap blocks, but he will face wham blocks. The difference between trap and wham is just who the blocker is - wham is applied by any non-offensive linemen - usually a TE or FB. Trying to trap block a 2i is risky because trap blocks take a tick longer to develop, and in that time an unblocked 2i can get on the QB in an instant.
Another point about the wide 9 is that since the DL is so spread apart, uncovered OLmen can more easily move to the second level. Here, the LT, C, and RT move up to the second level with little resistance.
Wham block applied by the FB on the 2i.
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If the 2i does something like this, it doesn't matter what the offense tries to do, runs aren't going anywhere.
While the majority of these cutups show a base defense (4DL, 3LB, 4DB), if the 49ers use this wide 9 in nickel as they have hinted at ("marry base with nickel"), then the same issues will be present in nickel.
Saleh about the switch to wide 9:
"We tried to marry base (defense) to nickel more. …We feel like we've been able to marry the two together so there isn't as much of a tendency. So to the players we might look more interchangeable, but we're actually no different than what we do in nickel."
"If you really go look at our season last year, we played 200-300 snaps of base defense. And in those snaps, I think we had like 50 snaps with the offense in two-(running) back all year. We did not see a lot of two-back. Everything is "11" personnel (three wide receivers) looks, spreading you out. They're just not letting us get into those formations anymore. If you eliminated third downs and you eliminated two-minute drives and it's just first and second downs and you looked at how many times a tight end was in a three-point stance on the line of scrimmage, it's not very much."
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He's saying that there were so few times when they faced base offense with an inline TE, a situation where the 49ers would matchup with their 4-3 under, so why not just play one style that works for when the offense goes base or 11? "Marrying base and nickel." Till death do you part?
