AC Milan this season has been quite active in the transfer market, Giroud may be considered as old players, but I still remember Jankulovski, seedorf, gattuso, Pippo, even though they are an old player, but he proved that he has quality and managed to bring AC Milan to the championship in the 2010/11 season. Giroud still has the potential to give the same thing. Milan have got Maignan, Tomori, Giroud, Ballo-Toure and are currently eyeing Ziyech, I hope Milan can do better this season with these new players.
Serie A is a league for old players but it is logic because in Serie A, tactics are most important and youth players there have debuts at older ages than in other leagues. You will not see players under 18 have debut in Serie A and go directly to the squad but you can see it very often in Premier League or Bundesliga or La Liga.
Giroud might not be a main striker for AC Milan because the position is allocated to Ibra if he is healthy. The transfer is a preparation from AC Milan for the retirement of Ibrahimovic.
Ziyech, I don't see chance for AC Milan to get him. He had a bad first season in Chelsea but the appearance of Tuchel will give him more opportunity in Chelsea. He is a good player and Tuchel can use him better than Lampard.