Manchester United management and Erik ten Hag worked together over the summer to transform the club's culture.
The Telegraph says United introduced a "no d***heads" rule in the transfer market under Ten Hag.
United brought in the likes of Lisandro Martínez, Christian Eriksen, Casemiro, Antony and Tyrell Malacia in the summer window.
But incoming boss Ten Hag was instructed to sign “no d*** heads".
That was at risk when they registered an interest in ex-Stoke forward Marko Arnautovic, known for his stroppy attitude.
It is said Bruno Fernandes, Harry Maguire as well as goalkeepers David de Gea and Tom Heaton have all acted as leaders at United.
And also the WiFi was switched off in a bid to force players to interact with each other.