The former Roma midfielder was speaking before tonight's derby against Lazio.
Nainggolan told Retesport: “It hurts. I had my best years in Rome, where we were always high up in the standings. Since I left, the Giallorossi team hasn’t played in the Champions League.
"I think Roma is improving but it’s still a long way off: there are a lot of points to recover and it’s not easy. It’s strange to see three coaches who think differently: (Leandro) Paredes, for example, didn’t play before and now he does, (Edoardo) Bove was launched by (Jose) Mourinho and then sold. Edoardo, given what he did in Florence, I would never have sent him away."
On Daniele de Rossi's axing, he also said: “It surprised me: it is evidence of the club’s incompetence. The club gave a 3-year contract to a coach who, that season, had done better than Mourinho by collecting many points and then the following year he was fired after 4 games. In short, it is inexplicable."