Middlesbrough manager Gareth Southgate has revealed that he knew it was time to let Yakubu Aiyegbeni go after the striker's poor performance in the 1-0 loss to Wigan Athletic.
Yakubu signed for Everton for a club-record £11.25million, penning a five-year contract at Goodison Park.
Southgate explained that the Nigerian was 'struggling emotionally', and it was having a negative effect on the team.
"The one thing you can't have at a club is a player who is unsettled to the point where it affects his performances because that then effects the whole team and that's the position we'd got to with Yak," Southgate told the club's official website.
"He was a smashing lad who I have no issue with at all but emotionally he was struggling and we saw that at Wigan, when unfortunately he gave a performance that was below his standards."
The Boro coach did not select Yakubu for the following game against Fulham, and he felt that lifted the team.
"When a player is unsettled to that point it's time to get the best possible deal for the club," Southgate added.
"That process was ongoing before the Wigan game, then we decided not to take him to Fulham and I think the team responded because of that."