The striker, on loan at Old Trafford from Championship club Burnley, put in a poor performance as Newcastle leapfrogged the Red Devils into third on Sunday.
Keys has urged Erik ten Hag to stop defending Weghorst and has dubbed the Netherlands international ‘Nout Workhorse’.
Weghorst has failed to register a single goal across nine Premier League appearances and has made just one assist.
‘I agree that they’ve made progress – but this isn’t a title winning side,’ Keys posted on his blog. ‘They’ll never win a title with Nout Workhorse in the side.
‘Seriously – why do they play him? His supporters tell me he’s doing something right because he’s starting games. Really? What is it then?
‘And don’t tell me he’s a ‘pressing monster’ or that he ‘starts the backwards press’ whatever that means.
🗣️ "[Wout Weghorst] is not good enough"
Jamie Redknapp believes Manchester United need a top striker 🌟 pic.twitter.com/iBe28idLOV
— Sky Sports Premier League (@SkySportsPL) April 2, 2023
‘Ten Hag justified his plans to sign him permanently by telling us that last week – and went on to add that Workhorse ‘creates space for players’.
‘I’ll tell you what – he’d create more space if he wasn’t on the pitch.
‘The bottom line is that he’s a bang ordinary centre-forward who doesn’t score goals and isn’t good enough to play for United.
Ten Hag sounds like a desperate man trying to justify a mistake every time he talks about him.’
Keys also ripped into Fernandes as he added: ‘A couple of other things from that match – Fernandes remains the most irritating player in the PL (Premier League).
‘Never mind applauding the travelling support – cut the play-acting, stay on your feet and try to affect games that way.
‘I’m pleased to see that officials have got the measure of him now. They know that if he goes over in the box he’s trying to con them.’