I going to write this, though fans won't really like it.
The premise that we can play both Pogba & Bruno in the same team in 4-5-1 is false, it can't & won't work against any decent team.
Pogba isn't equipped with any defensive ability or discipline to play along side Matic, Matic can't cover the huge spaces left behind Bruno and Pogba, especially if one of the FB went up to support in attacking phase. It just doesn't work. You can't simply claim that you want to play a dynamic style with 3 midfielders, one wants to press high (Bruno) while the second is clueless (Pogba) and the third is slow (Matic) in the counter press or even in high press. Let's not forget that our CB is slow as well (Maguire is slow, weak on 1v1 situations as seen many times against any fast opponent).
There's a reason why the system was working well just before lock down with both Fred and Mctominay behind Bruno, they provide the required balance, while both are limited in passing and vision, they are the best in work rate, covering, tackles and interceptions. All they have to do is pass the ball to Bruno who was alway lurking in between the lines or to one of the FBs.
Post lock down we had a nice run of easy games when we played Pogba/Bruno against easy opponents, but once we faced teams like Southampton, we started to struggle against high press, because Pogba literally crumbles under any sort of press, which is always a disaster when you try to play from the back, which is another thing we shouldn't be doing cause we lack the tools for, but let's not get sidetracked here. We attributed the struggling in the latest phase of the season to player being tired, while in fact, most of our key players were being substituted around 60 minutes, like every other team, and apart from City, every team played the same 11 almost in every game post lock down. So our player got tired, maybe it wasn't that, it was the system.
In all the games this season, there's a pattern in our high press, we press high with the front line including Bruno, but the double pivot of Pogba And Matic stay put because Matic can't do the running required and - in case the line was penetrated - run to recover or chase the opponents. This creates a gap between the two lines (front and midfield), in Tottenham' s game that gap was so bad that finally Solskjaer decided to ask Pogba and Matic to press high too, but the defense didn't press to reduce the space because would mean the defensive line would be too high for Maguire to run back as he suffers the same problem that Matic has, they are slow.
Solutions:
1. Pogba and Bruno is a recipe for disaster, they shouldn't play in the same team unless we play a very weak opponent, which is gonna be a rare occasion this season. We should play with 2 of Matic/Fred/Mctominay, where Matic sits deep and the one the other two do the hard work. One AM either Pogba, Bruno or VDB.
2. We shouldn't really be trying high press, that would require a very fast pair of CBs because you need a high line to maintain a narrow space between the lines, otherwise it's just suicide. While we at this, let's stop the half ass press we always do we asked the front line to press high while the rest of the team are acres behind. Let's just play with mid block.
3. Forget about playing out from the back, we simply lack any sort of discipline or understanding for this. When trying to play from the back against high press, one of the easiest approaches is La Valope exit which is usually implemented when your goal keeper isn't great with his feet. The idea is you need a 3 man backline to do that, so one of you midfielders drops between the two CBs who spread wide across the field of play while your full backs push up and hug the lines and the other two midfielder drop to create triangles of passing lanes. A perfect example was done by Tottenham against us before Martial was sent off. We ALMOST NEVER do that, and we when we try it it's usually Pogba who tries to do it, unfortunately he always drops late and receives the pass with him facing our goal, which is a big no no, that's why he keeps loosing the ball in this crucial area because he can't see the player pressing him from a blind angle. I don't think Solskjaer have the tactical capabilities to train our squad to this. So let's just keep it simple and avoid this completely. I'm tired of seeing Maguire running around like a headless chicken trying to find a passing lane, when the whole system of playing from the back is all about creating triangles of passing options!
That was along post, sorry.