And the former Sky Sports host believes from insiders that the situation is so damaging that Mourinho could be SACKED by Christmas.
Manchester United‘s build-up to the new campaign has been dominated by Mourinho’s clear frustration over transfers, which has brought his relationship with executive vice-chairman Ed Woodward into the spotlight.
The only arrivals into Old Trafford this summer have been Brazilian midfielder Fred, teenage full-back Diogo Dalot and back-up goalkeeper Lee Grant, leaving Mourinho incensed.
The United boss has whinged his way through pre-season, accusing Antonio Valencia of having too much holiday and pre-season being a waste of time.
And Keys is now understanding from sources inside the club that the players have had enough.
“United have stood still. I don’t like what I’m hearing coming out of Old Trafford,” Keys wrote in his personal blog.
“I originally thought Mourinho and United were a perfect match – but it seems he hasn’t learned anything from previous jobs.
“He’s miserable again. He’s tiresome again. He’s wearing again. He’s whining again.
“Jose – we’re fed up with it – but more worrying for United fans is that I hear his players are too.
“Right now I understand why he’s favourite to be the first man sacked. Unless things change I think he could be gone by Christmas. It’s almost as though he’s trying to get out again.”
Mourinho yesterday warned United face a “difficult season” if they do not strengthen their squad before the transfer window shuts on Thursday.
The Portuguese told MUTV ahead of his side’s pre-season friendly defeat to Bayern Munich: “My CEO knows what I want and I still have a few days to wait and see what happens.
“The other clubs who compete with us are really strong and already have fantastic teams. Or they are investing massively like Liverpool, who are buying everything and everybody.
“If we don’t make our team better it will be a difficult season for us.”
Mourinho and Woodward have been urged to put their heads together and bring the good times back to United by the club’s former chief executive Peter Kenyon.
Kenyon was a key figure at United during the glory years of Sir Alex Ferguson and has watched from a distance as the Red Devils have struggled to land the league title for the past five years.
Kenyon acknowledges things have yet to click two years into the Portuguese’s reign but does believe it can happen.
“They have to work it out and they’ll find a way of working it out,” he told BBC Radio 5 Live’s Sportsweek.
“United is bigger than anybody, bigger than any individual and that’s always been the mantra.
“It will get worked out and I would hope Jose is part of that working it out because he is incredibly skilled and he’s demonstrated he can do things.
“He is more than capable, one of the best coaches in the world but have they got it right? No.
“I think the first people to recognise that will be the people at United.
“Jose has all the capabilities, he’s done it, but I don’t think he’s in a place where he feels good at the moment, or United feel good at the moment or the fans at the moment.”