AC Milan is trying to build a team quickly, a practice they typically employ by combining senior and junior players. While the success rate isn't high, AC Milan has had success in the past two seasons, though not as impressive, considering the team's structure, it can be considered a success.
Modric may no longer be at his peak, but his experience is still crucial for guiding other AC Milan players, but that can only be relied upon for one or two seasons.
I'm not surprised by AC Milan's approach; they've always been this way of building teams.
After Milan brought in an experienced coach and brought in experienced players, even though they were older, Milan seemed eager to replicate their past success. As you said, Milan has always built squads like that, so it's no surprise.
Alegri will undoubtedly re-introduce a typically Italian formation, employing a flexible strategy that focuses on solid defense and fast, precise counterattacks. With this foundation, they will appear more tactical, disciplined, and focused. This can be seen in their transfers, a combination of young and older players.
In preseason, their performance appeared to improve. While this isn't a guarantee of a good performance this season, Milan's performance under Allegri has at least shown some improvement.