I think it's possible that many people are misinterpreting what EtH meant be "front and the back". In response to the question about midfield.
What if the issue is that the defence (back) aren't squeezing up and holding a higher line?
What if the issue is that the attack (front) isn't pressing very well collectively or holding up the ball well?
Both of these things can make the spaces in midfield seem massive. Both of these things can leave the midfield taking the blame.
Could it be that EtH knows better than the umpteenth cafite moaning about the midfield?
He speaks like that because this style of play, with its good and bad aspects, is what he was brought here to implement. Explain what and to whom? He made his name at Ajax by utilizing the same tactical ideas he's trying to implement here. Two attacking midfielders, both positioned very high on the pitch. Check. A more fluid left side with the winger either receiving the ball wide or tucking inside to occupy the left-half space and both the left attacking midfielder and the left back providing support and overloads. Check. The right-winger holding the width, the FB playing on the underlap and the right attacking midfielder being the 3rd man support. Check. He came one shot away from reaching the CL final with these tactics. . Yet, you have people pulling their hairs and screaming their lungs out about the supposed "madness" of it all.
As Pep used to say when he was on the ropes during his first season, there are only two possible outcomes: It will work in the end or it will not. But this is what he was signed to do. It's easy to "like" a particular style of play when the team is winning games left, right and centre. ETH isn't on the same level as Pep and Klopp. Nevertheless, he comes with a progressive tactical plan, one that tries to incorporate several of these two managers' principles and also one that's in accordance with most managers at top clubs are trying to do (some are doing well, some others are failing). The outrage, in this particular moment, is reactionary because, going by the posts on here, the answer is -almost always- to become more defensive, to fill the side with grafters, revert to reactionary football (to secure top-four or whatever means to "save our season") and a low block with Bruno trying to be a hero and Rashford chasing balls in-behind. But then, if you are not willing to take the risk, don't complain when other clubs move forward while we keep going around in circles, chasing our tails.
Going back to your post, you are correct for the most part. His tactics always left huge spaces open for counters because a) he wants to have as many players in and around the box as possible and b) he has a preference for dynamic positioning due to his man-to-man oriented press. The players have to think for themselves (and read the coaches' pre-match instructions) and adjust their positions to win the second/third balls and press/track the opposition players who pose the biggest threat, depending on the occasion. You don't get the high reward without the high risk in the modern game. Mourinho's downfall is proof of that. And striving to find a good balance in a high risk environment is the main reason the game is moving away from the "Roy of the Rovers" types to players who can deliver the goods while operating in a certain framework. Go where the space is, instead of expecting everything to revolve around you. Do your part off the ball, cause if you don't, the high press will collapse and we'll be in trouble. This is also why some fans complain about how sterile and unimaginative modern football looks, despite high scores and lots of chances. There's little room for pure and unadulterated individualistic brilliance (unless you have Ronaldo's numbers). It is what it is. It's currently not working. No, that's an understatement. It looks horrific. But not because Fred's not playing (don't make me laugh), the ever elusive central midfielder who will do everything on his own hasn't been signed (you'll never find him because he doesn't exist) or because we need to start getting everyone in front of the press in the build-up (yes, that's the most moronic thing you read on here lately). We need to make better decisions on the ball in the first seconds of a move in the final third, otherwise all these high turnovers we force will be for nothing. And we also need better reactions off the ball in the crucial first seconds after possession has been lost. And we need to get there as a team. That's what he has to figure out, if he wants to stay here after the end of this season.