The Portuguese coach, now in charge of Olympique Lyon, did not hold back when discussing why his project ultimately fell short.
"I'm disappointed, yes, because two years ago I was brought in for a reason: to change the team's style of play. 'We want Milan to become dominant, to have the ball and play in the opposition's half,' the club told me.
"Perfect, I replied, that's exactly my own idea of football. But the truth is that to change you need time, and playing that kind of football in Italy isn't easy. To succeed you first have to change the players' mentality. I might sound arrogant, but I was on that path and, after me, I've never again seen Milan produce the quality of football they showed with me on the bench," Fonseca said.
He also struggled to accept the star treatment given to his compatriot Ruben Amorim upon his arrival at the club this summer.
"I saw that Amorim arrived at Milanello and (Gerry) Cardinale himself was there waiting for him. When I arrived, though, there was nobody. I had been brought in to change the mentality. They didn't give me the time, but we played plenty of good matches. And after me it never happened again," he said.
Fonseca's criticism extended to the broader dynamics of Italian football, where he suggested certain players carry more weight than the clubs themselves.
"In Italy, players often count for more than the club. If someone, even a strong player, didn't deserve it, they didn't play with me. Nobody is bigger than Milan. Your idea of football isn't seen anywhere else. For 90 minutes you don't play and you defend, but if you score at the last minute and win, everything's fine and you're considered good," he said.
He drew a contrast with football development in his native Portugal, praising the country's approach to nurturing young talent.
"In Portugal we have the ability to work well with young players, preparing them to reach a higher level. We are the country that works best in this respect," Fonseca said, closing out an interview that leaves little doubt about the frustration he still carries from his brief and turbulent time in Milan, more than a year on from his departure and with Amorim now the man tasked with succeeding where Fonseca feels he was never given the chance to.