You don't think he tried all summer to sign Morata? You think he wants to play Phil Jones and Chris Smalling at centrehalf? Or buy young nobodies like Lindleloff and Bailly? Of course there's more to signing players than who the manager is and what he chooses. Lukaku, even with a set spell after moving to a bigger club, has only scored about 10 less League goals this calendar year than everybody's golden boy Harry Kane, he's no fool and will get circa 25 League goals this season. Not my cup of tea but still.
I'm not interested in defending Mourinho - he's won in the past because he's a good manager and he has the best players, he's no genius or particularly amazing coach. And, oh look, he doesn't have the best players and he's nowhere near. It's just Guardiola is no different and if you swapped their squads, Mourinho would be sitting pretty at the top of the League and Guardiola miles away making bitter comments about not having as good a team.