IMO this is the wrong way to look at it. IMO the reason they drop 7-8 is not because they don't fear the run game - it's because they fear the pass game much more than they fear the run game. This is especially true when you have a combination of 1. Exceptional QB with great receivers and 2. bad running game. In general the level of fear that teams should show is:
1. Fear of great passing attack
2. Fear of bad passing attack
3. Fear of great running attack
4. Fear of bad running attack.
And the distance between 1 and 4 should be light years! And when you get on your team both great passing attack and horrible running attack this forces opponents to send more help to cover.
It is not a coincidence that teams with great running backs like KC(before Hunt got banished) and the Saints(Kamara) and the Rams(Gurley) faced the least amount of stacked boxes ... this goes directly against what you would assume teams would do in a situation where they face elite running backs. The reason is - they just feared those teams passing games MUCH MORE! The passing game dictates how many people you send to cover much more than the running game.
And at the same time teams like Dallas, TEN, JAX had most stacked boxes - it's because the opponents didn't fear their passing game. I'm using just anecdotes here but the data overall supports that. The passing game strength overall dictates coverage vs run support much more than the quality of the run game. The weaker your pass game is the more stacked boxes you will see almost regardless of how good your RB/running game is.
I said 'almost' above because I can see a situation where you need to have some base level of a threat from the run. You need to at least be a threat to run it.
The short answer is ... weak passing game. Notice that this is all relative. No team will 100% leave 8 in the box and not team will 100% leave 8 in coverage. We are talking about percentages. The weaker the passing game, the more attention your run game will get from the defense pre-snap. This is alignment based... now once the snap is made the defenders have to read run and pass keys in order to know whether they should choose optimal strategy for run defense or pass-defense. In general the reason play-action(and RPO) works is because of the THREAT of the run, not the success of the run(it doesn't matter if you run it for 4.2yards a run(where we were last year) or 4.7yard a run(where Reich wants us to be). So ... my point is not that you have to completely ignore the run. You don't ignore it. You still have to keep the threat that you will run it(by running it often enough) in order to make the defenders still read the keys and give you the extra second or so that running the play action gives you while the defenders are reading the run key you are giving(faking to) them. You just don't generally care much if you run for 4.7 or 4.2 when it comes to your passing game or your play-action game. Teams react the same way to 4.7y teams as they do to 4.2y teams when it comes to play action as long as you keep the threat that you will run high enough to make defenders still read their run keys. (now this is another thing I have not seen yet, but expect at some point in the future- some defensive coordinator will say - just screw it - play the pass 100% and don't read the run keys... play the run on your way to the passer and I don't know what will happen then)
Well, that quote is a bit of an exaggeration to bring the point across. You won't really wait for the old timers to die out. Just... the more young blood comes in(Shanahan, McVey, etc.) and tries the new stuff and succeeds with it against the old strategies the more the old timers that are unable to adjust will lose their jobs to the new kids and so on. This pretty much already happened in the NBA. It's a new league now compared to just 5-10 years ago. It didn't happen because the old timers died out, it happened because the new strategies proved better and more efficient and even some of the old timers borrowed from them and incorporated them into their game plans. IMO similar things are happening and will continue to happen in the NFL. It probably will take longer because in general the NFL seems more conservative of a league but IMO it will happen sooner or later.
In 20-30 years I think we will be laughing at things like "establish the run" or "first we need to stop the run", just like we would be laughing at statements like "what this team really needs is more post ups for their center" or "this guy should have just taken one dribble into the 2p range and taken the shorter 20 feet jumper instead of the 24 feet open 3" in the NBA-context right now.
"But really what is going to set the tone for us is going to be how we run the football. That is not going to change. We have to run the football. Our goal is going to be a top-five rushing football team. That will set up our play-action pass. That will set up all the big chunk plays. To me that will get us where we want to go.”
Just as Reich has stated above I do believe a good ground game opens up more favorable passing opportunities because teams have to committ more personnel than they would like to run defense. That in itself sets up more opportunities for you to get one on one coverage down the field. I think you get less of those opportunities if you can't run. If I want more one on one coverage down field I'd like to know how I'm supposed to do that if I don't need to run? I guess maybe you'd say screens or something? I'm sure he's saying this based off what he's experienced during games and what he's seen on film.
One of my issues and I belive Princeton Tiger brought it up also was when your running game is not very effective. For example in Peytons last years in Indy our run game was abysmal and teams literally ignored all of our play action fakes. Or you can even look at some of our seasons under Pagano. They dropped 8 and rushed three a large majority of the time because they had little fear that we could do anything on the ground. Do you think that happens to us with a successful rushing attack? I personally don't believe so.
I think when you are able to run it forces the defense to leave less defenders in coverage. I don't want to turn this into a long drawn out debate but I believe your contention was it isnt the amount of times you run but more of the effect of the play action itself. So when the defense is ignoring the play action then what is it that would cause them to honor it again? I believe you would have get some kind of success from your running game which enhances those play action fakes. It's not just the play action fakes themselves. I don't really think you need any type of data during a game to tell you that if the defense is committing 8 men or more in the box you've got a better chance of completing passes on the defense. What causes the defense to committ 8 to 9 men in the box? A successful running game gets them to do that more often than not. I think it creates more opportunities for you to face lighter numbers of defenders when you want to pass the ball. I got to be honest here and say I can't go toe to toe with you on all that stat crunching, but there's just a few things I will just never buy about that data. And if you're waiting for bodies(us old school thinkers) to die it's going to be a long, long, long time before that happens in the game of football.........