The result summed up United's season perfectly despite some mid-season heroics when Ole Gunnar Solskjaer was first given the reigns. These two sides met earlier this season in Ole's debut, and Manchester United cruised their way to a 5-1 win thanks to goals from Jesse Lingard (twice), Marcus Rashford, Ander Herrera and Anthony Martial at the Cardiff City Stadium.
"We've been poor", Solskjaer said.
"The end of the season makes it clearer than when we had that great run of form". We got a few injuries and it's been ups and downs for the last two months, but that's football. Do you think Solskjaer is right?
He's still playing, with Stoke City, but is expected to announce his retirement at the end of the season. "That's where we are at the moment, but we're ready for it, the fans, supporters today too". "We finished five or six points behind third, fourth and [four behind] fifth, and that has to be our aim".
"He is one of the best people I have ever met in football".
They could yet finish the season 32 points off the top of the table and Solskjaer is well aware of the job facing him.
"That is not where our challenge lies, we have a long and hard way to be where we want to be".
"Last time we were in the Europa League with Jose (Mourinho) and loads of these players, we won it".
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But the big question is whether the 23-year-old can have the same sort of impact as Eden Hazard? "But at the moment I don't know". Hazard has just a year left on his contract having joined Chelsea from Lille for £32m in 2012.
"So next season, yes, we've got to close that gap".
Manchester United's miserable season ended in a whimper, as already relegated Cardiff City stormed the Theatre of Dreams to claim a 2-0 win.
The United manager said: 'Players really respect him, they know what he can do and he's worked with the best. I'm happy with the communication and the targets we've put up and now hopefully we can get some over the line.
"I didn't want it to be a damp squib. I don't like when other managers talk about my players and I wouldn't talk about any others, even if I wasn't or was interested".
"I always thought our front four could cause them problems and I thought we did".
Warnock is adamant he will never manage in the Premier League again. "I've not gone to bed one night worrying about what's gonna happen because I love coming in, the boys are fantastic".
"They have wasted a lot of money", added Warnock.
Manchester United suffered disappointments in the cup competitions as well after the Red Devils lost to FC Barcelona and Wolves in the Champions League and FA Cup quarter-finals.