What are you talking about? We're 3 games into the season and we start talking about rotation like it's some magic wand that resolves all the injury problems, but it's not.
Injuries happen and it's impossible to predict who gets hurt and when. Chiellini tore his ACL during an ordinary training, shit happens.
Take Man City for example - they're left with one CB only for their CL match. Laporte out for 6 months, Stones 5 weeks. Shit happens, life goes on.