Middlesbrough boss: Yakubu had to be sold
"Emotionally, he was struggling, and that performance at Wigan was below his own standards," the Boro boss told a BBC Tees fans' forum.
"When a player is unsettled to that point, it's time to get the best possible deal for the club."
He added: "That process was ongoing before the Wigan game - we decided not to take him to Fulham, and I think the team responded because of that.
"No one player is more important than a football club."