Alan Pardew has hit out at the negative impact that WhatsApp group chats are having on dressing room atmospheres.
The Facebook-owned messaging service is used primarily for talking within groups and has become extremely popular with football players.
It is common for players to have their own WhatsApp group chat that does not include members of the coaching staff.
Speaking on a podcast titled A Pint with Eamonn and the Gaffers, Pardew said: "Now, when players are leaving the training ground, they're not leaving the training ground, they're WhatsApping each other and it's now toxic and spreading throughout the whole group, bringing people in.
"Suddenly, you arrive at the training ground and there's a strange atmosphere and maybe they've all made a different outcome to what you as a manager perceived the outcome.
"And it's completely out of your control, of course. You can't infiltrate it; you don't want to really because then you're asking for even more problems I would guess. The senior players and toxic players now have a bigger control over the dressing room."
Pardew's last managerial venture was at West Bromwich Albion, during which the Englishman oversaw the Baggies' relegation from the Premier League with an awful four-month period of results.
Leo Nieboer
