Whitehead backs Sunderland boss Keane over Miller transfer-listing
Whitehead said: "The manager's his own man. He goes about his own job the way he does and the players enjoy playing under him. We know what he expects, what he demands of his players and if you slip below those standards, there's going to be problems.
"Have I ever been late? No, discipline's a big part of football. Being on time for your team-mates, making sure you don't let your team-mates down and show a bit of respect."