Agreed. I'm not even a fan of McTominay and do think he is probably the weakest position of our starting 11, but we would have looked a lot better with him in there instead of Matic.
A huge part, probably the biggest part, of being press resistant as a team is always having passing options to give it to. The single most important part of the team that contributes to that is the midfielders, always moving and making themselves available to pass to. When one of the midfielders spends the entire time sitting in the defence, leaving a huge gaping hole in the middle of the field with one player trying to do all the work, it's going to be a huge issue. It doesn't matter if it were Xavi, Scholes or Keane, one player in midfield is going to find it incredibly difficult.
It's actually one of my biggest issues with Scott as he is quite poor at making himself available, but at least he is in the midfield providing a number.