They sign them and don't even play them (Giaccherini was a bench player).
Honestly though, Serie A players aren't typically suited for the English game. No other country plays football like England. While it may be more exciting at times, in no other environment do teams play that back and forth. I remember when Mancini was playing a more conservative game, he got branded boring. If you compare World Cup football to EPL football, it just shows that in no other league do teams play so wide open. Frankly, Serie A players that go over aren't used to sprinting back and forth over and over again.