Cook in reality played very little test cricket with Ballance and the major amount of his 100 plus tests with Kevin Pieterson.
england are playing virtually all year round so it's not really surprising players form friendships and tolerate each other if it goes the opposite way, look back thru history not everyone gets on with each other, Gower and Gooch for example hated each other.
Whilst I don't like some of what KP has done the role of Swann,Anderson and Broad and maybe Prior has to of played a role in what happened in the dressing room,quite what role no one really knows,but you are talking about well established senior players who will have a lot of clout.
Flower was very regimented, Pieterson has the opposite character.
For example if the Ashes series we lost 0-5 Flower wanted extra nets,extra training,extra practice, Pieterson in that case argued strongly for 'working on skills because that is letting us down'. KP himself said this many times in interview.
In that case where you have two options to work on,which one would you choose?
So it's not all cut and dried with KP..