Karanka style was abrasive and he fell out with many people in his time at the club, culminating with the Charlton situation.
Many other players would echo Carayol’s sentiments toward Karanka, but he got results and that was the only thing he was interested in, I heard an interview with Dean Saunders reflecting on his time as a manager and he said he could never make the detachment and be ruthless enough toward his players and that he always tried to maintain a friendly relationship with them which meant they treat him as a soft touch, Karanka was the opposite and I’ve heard tales of him blanking players in restaurants for example.
Karanka is not in football to win friends but win games and at times that singlemindedness ruffled feathers.