Their personalities have rubbed against each other for a while now. It played out behind the dressing-room door, away from the cameras.
Outlook
Repeated incidents may damage dressing-room status.
Stayed back for extra training
Moderate
Cause
He stayed back for extra work after the rest of the squad had gone in.
Asked the manager for a private conversation
Moderate
Cause
His relationship with the manager has soured. His relationship with the manager is steady but tense. He has already raised this with the manager recently.