Think it's both Fabregas and Matic that's at fault. Neither are at their best but the setup isn't helping either. Matic has looked quite erratic in his play, but Fabregas has looked quite poor both offensively and defensivesly. Fabregas himself has caused a few misplaces passes in key positions, although Matic himself needs to improve his ball playing which would ease the burden off Fabregas. All in all, although the partnership worked last season, there are a few weaknesses.
I believe when he debuted he was partnered with David Luiz (and was there a few times) which looked like a pretty damn solid partnership. With Ramires it was alright as well -- not a great deal of creativity but quite robust in midfield.
Think this isn't too much of a concern though. He'll be good again. Perhaps this is why we're looking for a marquee CM though.
I don't think so. Most teams who play a 4-2-3-1 play with a defensive line closer to their midfielders. We just need faster defenders I think.
I understand what you're saying & I agree, but it's not even the space between the two; it's more the fact that players can get an easy run in on the players generally. Against West Brom for example, there was no space to play through our mid but they troubled us because they could run at us quite easily. When we do decide to push and then press they just hit us over the top with a faster player, which is why, like you said, we need faster players to match those runs.
Alternatively we've got players capable of high press runs ourselves so we could do what Barca does and aim to win the ball back in the final third.
Also would suggest why not only we're keen on Pogba (or so the rumours say) but for Stones as well. If we do buy Pogba though then we'll need to switch to a 4-3-3