We've never signed 6 players in one window under Mourinho and the papers get plenty wrong. Only way we would have signed two centre midfielders in my opinion is if Fellaini had left.
Mourinho couldn't have made it clearer he wasn't interested in an attacker in February. Things might have changed since then but we weren't really heavily linked with ones during the summer - there was the standard Bale, Willian and Perisic mentions then the odd 'weird' name like Mandzukic, Arnautovic and Rebic but those connections were all brief. Think Mourinho would have wanted us to go for Willian if he was available (from what Willian was saying about Mourinho constantly being in touch) but Willian's gripe at Chelsea was Conte and there was never that desire for him to leave after Sarri was brought in.
There wasn't much said in the papers about leftbacks either and Mourinho and Shaw's quotes suggest that wasn't a priority either.
We got the right back and one midfielder part, but failed on the centre back. We got the midfielder and right back done early but seemed to be a lull during the World Cup before we went into a centre back scramble in the last few weeks of the window. I'd guess the problem there was we expected Levy to lower his demands for Alderweireld but he stood firm.
I don't think we'll ever really know why this window went so badly unless Mourinho does a Moyes and talks about it in a few years if he's at another club.