AC Milan have really spent a lot of money to strengthen their squad. As we all know, Allegri's teams start off terribly and then improve as they go, so in my opinion we need to wait a few weeks before we see the real new AC Milan.
But maybe Massimiliano Allegri won't succeed this time, who knows?
You are right AC Milan has spent much of money to improve their team and with Massimiliano Allegri as new coach we should have to be patient. Allegri teams are known for starting slowly and getting better as season goes on so it will take few weeks for players to fully understand his style. His past success gives hope for good season nothing is guaranteed in football and only time will tell if his methods will lead to success this time or not.
You are right to, Milan spent a lot of money and made some good signings. For example, they signed 39-year-old Modric. We know Modric, even at 39, will be beneficial for Milan he can come on later in the game and bring results, and they can also benefit from his experience. Allegri can use him late in the game.
There are also good signings like Jashari and Nkunku. For now, Milan has started with one win and one loss, it's too early to comment the players and manager need time to get their act together.