Wait, does it mean Manchester United is selling out Onana? Although I haven't really followed the Manchester United transfer trends or rumours to have a clue as to whether he will be transferred or not. Aston Villa goal keeper is Martinez, if Manchester United wants some new players in their ranks and Martinez is part of that new team, then it's definitely going to be a good signing for the club because his a good goalkeeper with a track record.
They need to replace Onana at their main goalkeeper position but keeping or selling Onana, it depends on whether they already have a good one as a second goalkeeper if Martinez gets suspension or injuries. Onana is not good enough for a main goalkeeper position but for a substitution role, I think he ca do it well.
Man United needs a goalkeeper who can be relied on, especially when facing a match with great pressure, and I don't think Onana is the man. Emiliano Martinez could be a good option, while Onana seems better off being sold, and Bayindir remains as backup.
But the problem is whether Emiliano Martinez wants to join Man United, who are known not to play in Europe, or whether Man United is willing to spend a lot of money on him, considering that Martinez still has 3 years left on his contract with Aston Villa.