Actually AC Milan was also not very good last season, they finished in the runner-up position because Juventus recorded 14 draws, from the number of defeats AC Milan recorded a greater number. In addition, AC Milan was eliminated too early in the Champions League, and they could not go further in the Europa League after being eliminated by AS Roma. Due to this reputation Stefano Pioli was fired and his new successor Paulo Fonseca has not shown any signs of improvement so far. Meanwhile, Juventus, who only focused on domestic competitions last season, ended the season by winning the Italian Cup trophy, although not so prestigious it can be entertainment for fans. However, Allegri managerial career was not saved due to his reaction which was considered excessive, and Thiago Motta who was appointed as the new successor seems to bring a breath of fresh air this season, it can be seen from the three matches they have gone through without defeat.
It seems that this season Inter Milan is only getting pressure from Juventus, although it is too early to say, we'll just have to wait and see.
I agree that Juventus was much better 90% of the season, I mean even the last four games were draws for Juventus, if they had like just two wins there instead, they would have been tied points, that's such an important difference, Juventus finished the season terribly and that's why they were third.
Milan isn't terrible, and they changed their manager, so I think they could need some time to get better adjusted with the managers system and maybe they can get better too. I think they will still finish high up, not sure at what place but once again a top four would make sense to me, I would believe that it would be a good thing to see them there because Milan spends a lot to be there, if they fail to be there then it's going to be a trouble for them and not going to benefit them financially.