Fair enough mate. I see now that you were not referring to the central midfield specifically, but more to the way we set up as a team.
I agree that Silva, ideally, would prefer to play 433. But when he took over as manager last summer we arguably had only 2 quality players on the books who could fit seamlessly into that system. One of them, Gueye has since left the club and the other, Walcott, has completely lost his mojo in front of goal. We brought in a couple of players last season in Richarlison and Gomes who fit the bill but, with losing Gana, we still only had 2 quality players out of the front 6 to play that system, and we also need at least 2 quality back up. So we effectively needed to bring in 6 new quality players if we were going to be able to switch to 433 as our main formation. I think it's fair to say that is too much to achieve in one window, even if we had an open cheque book which I don't believe we did.
The other issue, as you rightly point out, is Sigurdsson, a high quality player but one that does not fit comfortably into a 433. Not only is he currently our most creative player but we also rely too heavily on him for goals. Silva has to replace his goals amongst our front 3 before we can even think about offloading him. Then he also needs to add more creativity to the midfield 3. Again, this cannot be achieved in a couple of windows.
We have taken steps forward this summer with players like Gbamin, Iwobi and Kean. Had we managed to bring in Zaha and Doucoure on top then you could argue it was job nearly done. But I honestly don't think we were ever close to achieving that.
I think you are spot on in that Delph was brought in as a short term measure, to help oversee the transition from 4231 to 433. I think you'll see a mixture this year. 4231 when we expect to dominate possession and 433 when we expect to play on the counter. It's going to take at least another 2 windows, given that our main transfer priority now is a quality back up central defender, but hopefully we will be there r thereabouts by the end of next summer. I think we've missed out on Zaha now as I believe Chelsea will be in for him possibly in January. But we need a similar goal scoring wide man like Neres or Lozano, plus a couple of midfielders like Sangare. This Jesus lad in January would be amazing if it happened, but that's pure fantasy at the moment.
Basically what I'm saying is that Brands and Silva needed at least 3 summer transfer windows to complete the transformation of this team to what Silva wants. In my opinion we are just about on course to do that and are possibly 3/4 players short of what he needs.
At some stage though, if we are to seriously challenge for the top 4 positions, either our young players need to take the step up to the next level, or we need to start bringing in players of the proven calibre of Zaha for serious money and on serious wages.