I think we thought that Matic would have enough to cover it for this season and then slowly start to phase him out. I wonder if something has happened after he signed that contract as he's been in and out of the team ever since.
Also, last season we were much, much more solid and didn't give up anywhere near as many chances as we have done at times this season - a large part of that was due to Matic, as well as Fred and McTominay at certain points. I think Pogba's return has muddied the waters a little as up until then, we seemed to have got the balance just right with Matic and Fred/McTominay in the double pivot and Bruno ahead of them, as the workrates of Bruno, Fred/McTominay compensated for Matic's lack of legs.
Maybe they also thought that while the DM was an issue, it wasn't as pressing an issue as getting the Grealish/VdB player to help us unlock tight games?
Who knows, we just have to make do as best we can with the players we have available. Here's hoping it goes well. On the bright side, our midfield options last year looked a hell of a lot worse than they do this time round