I have never heard about any conflict with Branca, Valdano was at fault imo, and he worked fine with Emenalo until the john stones saga.
So I dont see it as a problem with DoFs per se but (like we have seen this season) he doesnt react well to his transfer requests being ignored. That would usually involve the DoF.
As much as I disagree with his petulant handling of things, in both Valdano and Emanlo cases,I believe he was in the right. A good DoF should be helping the manager not working against him (valdano) or back seat coaching (Emenalo). If at any point you dont trust your manager's judgement on what the squad needs, then you should fire him, not work to undermine him.