I agree. Because if we compare Inter Milan and AC Milan, there is a clear difference, especially at the end of the season. Inter Milan is far more consistent. They even got better at the end of the season.
In the past season, their difference is very small from their standings in Serie A to their results in Champions League. Inter Milan won against AC Milan in Champions League semi finals and that's all. They played one more match, the final and failed even they did played well in the final. In Serie A, they are at the third and fourth position on the table at the season ending so no big difference at all.
And speaking of the last 9 seasons, it is true that Inter Milan is still much better. It's just like you said that AC Milan has improved in the past few seasons
The performance of AC Milan got improved since the appearance of Ibrahimovic in San Siro after about ten years. He enlightened many young players in AC Milan and boost them to play better. We saw how AC Milan young players admired Ibrahimovic a lot and gave that Swedish striker very high recognition when Ibrahimovic had a farewell on the field weeks ago.
and in the season that just ended Milan almost lost a ticket to the Champions League.
They got it and that's all. It's not big deal how they got it. Both Inter Milan and AC Milan struggled in that race and they only got those positions at very ending weeks of season when Roma, Juventus got point reduction and Roma paid more resources for Europa League.