I mean obviously he isn't a world-beater, he's a bet. They signed new people (including Dybala, as Andrius said) and have less room/budget for him. Of course he's not a signing who you're sure would do well, but players perform differently in different teams. If Conte wants him, it's because he thinks he can use him and make him play well.
Kulu and Bentancur being perfect examples.
Agree that Conte is a fan, and Roma have done a ton pf money this window so i guess someone has to go and for decent money.
I just cannot see Maddison coming to Spurs, and the next best available option is Zaniolo.