As I understand it this is a 4-3 defensive scheme, where the most important positions are the three technique and the strongside, weakside, and middle linebackers.

This is specific to the Tampa 2 style system that Eberflus runs. For example. Greg Blache, a bears DC from forever ago, ran a 4-3 system that used 2 2-gap DTs (think 2 Andrews Billings) and no 3T.

What makes it outdated?

There is a balance between complexity in a system that is hard to figure out and simple systems that allows athletes to play quickly. Eberflus’ system is super simple. Offenses have evolved in the last 20 years and OC know how to pick apart what we are running. Eberflus has no creative scheme fixes to cover its flaws. Its not that cover 2 (the tampa-2 is really a cover 3, but thats a whole other story) plays can’t be called. Its that basic cover 2 with nothing to change it up can’t be called on repeat any more.

This system was one thing in Indy where he was getting by without much talent and using lower draft picks. But now that he has high draft picks and high priced FAs, he has shown that there is no next level to his defense and even Indy was a bit of a mirage. He doesn’t do much to disguise coverage, but there isn’t much variability so I don’t know how much it would matter

Is a 4-3 not usable anymore in the modern NFL?

It is usable, just not the super vanilla system Eberflus runs.

And what will happen when Eberflus is sacked, which looks more and more likely by the week. Is it easy to transition to a different scheme or will the defensive roster be stripped down due to scheme fit

If we switch to a 3-4 a coordinator will say something like “it doesn’t really require that much personnel change” and then spend the next 3 years flipping the entire defensive roster. Some players lime Montez Sweat would probably be able to play standing up, but you are getting 90cents on the dollar for the position change. Most of front 7 would be replaced.

If we stay in a 4-3 its smoother. I hated the Edmunds signing at the time and it looks worse now. Most 4-3 systems don’t require a super athletic middle linebacker, he is superfluous at best. If he plays well he will be traded for a low draft pick. More likely he is cut at some point in the future to get out from under the contract.

Our CBs are fairly system agnostic and would be ok in a more press-man system.

Lol, lotta dudes that don’t know shit about shit acting like they know shit.

You’ve gotten some good answers already but let me add my take also. There’s a lot of misconception about the defense being run. It’s a cover two, soft zone. However, unlike Lovie’s old Tampa Two they do change up coverages to fool with the QB presnap reads. The problem is the nature of the zones they play. Like I mentioned they are soft zones, designed to allow short passes but take away the deeper passes. It’s outdated for that reason. It used to be that QB just wouldn’t be patient enough to take the 5-7 yard passes, now they are and most West Coast Style of offenses add an element of running after the catch that hurts this type of coverage. It’s also fairly weak against the run unless your DL is very good.

However, your concerns about them making major changes to the basic structure of the defense if Eberflus is fired are probably not something to worry about. Unless they also fired Poles (which would be a huge mistake) he’s going to bring in a coach who will use the same basic defense but perhaps a bit more aggressive and flexible. The same is true on offense as well.

The people that don’t understand this forget that this was the plan from the beginning, they were going to tear everything down and build in back mostly through the draft. Clearly they expected to see better results this year which is why Eberflus may get fired but there is a plan in place and they are going to stick with it.

Is there a defensive scheme that is able to counter current offenses? Maybe some kind of hybrid cover 3. But from my understanding it’s just getting pressure and disguising looks. There’s not one main defense that a DC can rely on to stop an offense all game.

Well when they drafted they didn’t necessarily draft for perfect fit. Like the two linemen. Dexter/Pickett. Example. They drafted on metics they put a premium on, size, speed, athleticism, arm length, smarts, hustle, ummm… oh and Character and play making. And then develop them to their scheme… pretty much Not to do what they do Best. Lol so here we are.