I don't get where this idea has come from that Rugani has been a disappointment. He's been fighting for playing time behind some of the best CBs in football for 3 years.
This year he played Milan, Roma, Lazio, Inter away matches. Barcelona home match. We won 3, drew 2. Scored 6, conceded 2 goals in those 5 matches.
In 16-17 he played in Sevilla away, Roma, Inter, Milan home matches. We won all 5. Outscored our opponents 7-2 in those matches.
In 15-16 he played Napoli, Inter, Lazio home, Milan, Fiorentina away. We won all 5. Outscored our opponents 10-2.
We haven't lost a single match in 3 years against a top team with Rugani. In 3 years he has played 59 Serie A and CL matches for us. We have lost 3 of them.
With Rugani: 54 wins - 3 losses - 4 draws.
But he's disappointed.