Fine timing as usual, Cron, considering that Inter signed Gagliardini from Atalanta for a similar kind of fee with bonuses an entire day before we signed Caldara. The difference with them is that they need players now - we're good and stacked in that position, Inter are not good and need Italians.
Attackers are expensive, because they are rare and can make the difference, midfielders are not as expensive as them and defenders are even less expensive. They overpayed as well, but less so because he is a midfielder and as you said, because they actually need him now and when you want a starter in the middle of the season, when tge market is lethargic and it is harder to find a successor, you might pay more.
I believe that they will regret that move, but they had to gamble, we dont.
With those 25 mil at hand for 6 years, an opportunity would arise for a player of greater quality at the end of his contract, or maybe a new even better talent.
Beppe might of course have some special reasons to buy someone from this generation, maybe he has calculated that is exactly the age the Chiellini successor must have.
Italians defenders used to be the best in world and Italy had a continous production of super defenders, but after Chiellini and Barza, it seems that thats it. Buying the best domestic product of a generation is not what it used to be. There was a time that this was true but not anymore. With 25 mil at hand today we can get better and proven CBs from Germany, France and Holland.