Milan have done a really good job by taking advantage of Juventus' bad form recently. They are at the second position now after this. I find their productivity quite decent this season compared to their nearest opponents like Juventus and Bologna. The main problem is more related to Milan's defending. They have conceded 33 goals in 29 games. 
Acmilan was not missing an opportunity to secure a spot in the UCL next season. Who knows if a coincidence is happening here. Juventus performed very well when Acmilan was bottling so many games, but this time, Milan did very well in so many matches while Juventus bottled some matches. It seemed to me that Juventus's loss against Intermilan was totally impacting their performance. The players had mental breakdowns, which also prevented them from giving their best performance. It was unbelievable to see how Juventus climbed very fast and is now dropping so fast as well.
Juventus reached third place, and the UCL as well, directly groups, so that is about 30 million euro give or take, and I believe they do not feel like they need more. Dbet or not, they have a good squad and they can keep this going. Italian teams were never know for spending insane amount of cash on players, they are usually teams that end up with good results while spending less.