Speaking to GamblingZone, Gullit said, "Reports of dressing room leaks will be Erik ten Hag's biggest concern. When I was at Milan, nothing ever came out. That's why we were always so solid. Leaks aren't good for the team. Players may think things like this can help them, but people always suss out who's responsible for it. You're in big trouble after that happens. It also hurts your chances of joining another club, as they'll know what kind of guy you are if you're comfortable leaking things. It's not good.
"Whether there's any way back for players after they start leaking information depends on the terms the person was on. The coach will know who's leaking it, and the players will find it eventually. It's the worst thing a player can do. If I found out one of my players was leaking information, then I would have waited for the right moment before I dealt with it! That's what managers should do. They know how it works. A manager is always right when they're getting results. The manager should always wait for the right moment no matter what action they take. You could take big actions or small ones. It depends."