Michael Carrick has admitted that things "just didn't work" when David Moyes was manager of Manchester United.
Moyes succeeded Alex Ferguson after he stepped down at the end of the 2012-13 season, in which United won their 20th top-flight title.
However, the former Everton boss endured a dismal campaign at Old Trafford and was sacked following a 2-0 defeat against his old club in April 2014 - a result that ensured United would not qualify for the Champions League.
Carrick has denied that there was unrest in the dressing room during Moyes' tenure but has conceded that the season was a difficult one.
"It was a tough time. I think we can all say that with Sir Alex leaving and the changes that happened after that. It was a tough season, there's no getting away from that," he told Sky Sports News.
"We had some success in the Champions League and we weren't too far away from getting past Bayern [Munich] in the quarter-finals so it's fine margins I think. When you look at it, it just didn't work that season and we didn't have a great season in the end.
"Unfortunately for David, he lost his job so I'm sad how it finished but I suppose that's football. If you don't get the results, and you're the manager, you suffer for it.
"Of course it was going to be a tough job to take, but whether it was impossible or not, I'm not sure. I wasn't sitting in that seat and I wasn't in the position to be manager. You'd have to ask him I suppose.
"Just because it's tough times, it doesn't mean there's fighting and you don't get on or not like each other. Sometimes things just don't work out for many different reasons and that was the case."
United face Moyes' Sunderland on Sunday looking to bounce back from back-to-back draws against West Brom and Everton, which have put a major dent in their hopes of a top-four finish.
But Carrick is confident that manager Jose Mourinho has instilled a drive for success into the squad, despite their disappointing league campaign.
"You can see that Mourinho is a winner and he's won wherever he has been. You can see that it drives him on and it's all about winning and rightly so," he said.
"That's what you want, you want to be winning things and be successful. We're still a bit short in the league but we won the EFL Cup already and we're going for another one. He's driving for that and he's hungry, you can see he's hungry for more and he wants more success."
Carrick's long-term future remains in doubt, with the 35-year-old yet to finalise a deal to extend his contract until next year, but the former Tottenham man says he will not leave United for another club in the Premier League.
"It won't be anywhere else in England [next season], no. I've had too many good times here to do that elsewhere," added Carrick, who will have a testimonial match in June to mark 10 years at the club.
"I've said it for a number of months now, I'm just really enjoying playing football. When you get to this age and you come closer to the end, obviously you get asked these questions but I'm just trying to play and compete in the team and be part of the squad and see how long that takes."