Mexes had some standout performances last year under Pippo of all people lol. Better than anything Romagnoli has produced so far..so yeah.
He's been good, not great. Don't quite get the hype yet, guess it's because he's young.
Romagnoli doesn't make catastrophic mistakes. And in the modern game, finding a defender that doesn't commit huge fuckups is super rare. That Romagnoli has this knack is why he is so prized, in my opinion, especially because he is young and can still grow into getting all the nuances right.
A lot of high caliber teams are willing to content themselves with Zapata-tier players who will defend very well but give away games ever so often because of lapses in concentration or for simply screwing up something basic. If Romagnoli can defend like Zapata on his best days and also be consistently safe and without being prone to errors, then he'll be one of the best in the world. I mean, consider Jerome Boateng, who I think is probably the best defender in the world - why did people grill him for getting massacred by Messi earlier this year? Because he never gets massacred by anyone. He's consistently solid, and his performance ceiling is absurdly high. Romagnoli can get there, he just needs a better coaching staff behind him and a stronger squad around him. This is why Costacurta mentioned today that Romagnoli would become one of the best if he had played alongside him, Maldini, Baresi, Silva, etc. etc.