The midfielder was offered a new contract after his deal expired, but believed his time at San Siro was over and has now joined Swiss team Sion.
“The locker room was out of control in the last two or three months with things I’d never seen in 13 years with the Rossoneri,” Gattuso told France Football.
“The rules were no longer respected and the older players, who were irritated, no longer had the strength or the willpower to tell their teammates off. At that point I realised it was time to leave, even though the contract renewal was already prepared.
“When we had training at 9.30am, many arrived just 10 minutes beforehand and nobody would say anything. I’d arrive 45 minutes early in order to do some exercises, get a massage or even just to relax with a cup of coffee. That’s the sporting culture you get after years of experience.
“Or, when we had lunch at 13.00, some turned up 15 minutes late. There was no respect for the rules.
“If in a group of 25 players the rules are not respected, then it’s immediately chaos. These are things that sap energy from the older players too, as they get irritated at wasting time criticising the others.
“The thing that really annoyed me was that nobody said anything. I no longer felt like Rino Gattuso in that locker room, so I realised it was time to leave.”