Onana - The only question marks around him should be about his shot-stopping, but you know what, I wouldn't even say there are question marks about it. He's average at that, and will likely never even be close to world class. However, at everything else he's good-to-great IMO. Commanding the box and his defenders, coming out for crosses, passing, press-resistance. Especially at the latter two, you'll struggle to find anyone better than him across world football, let alone someone who would be attainable for us. If we want to become a team that cedes possession, concedes chances every game, doesn't want to control their matches, and heavily rely on the shot-stopping capabilities of their keeper, then by all means we can ditch Onana and bring in someone who's inferior at everything to him but is a great shot-stopper. However, if we want to play the modern way like most top teams do these days, then the strengths of Onana I listed above have much more importance than how good he is at saving the ball. In fact, those things he brings to the table are absolutely essential if we want to play out from the back and be able to play out of high presses. Just watch back his performance at Anfield in December as a great example of how valuable he is. It's also why City employ Ederson despite him not being one of the best shot-stoppers around, and the same goes for Arsenal with Raya and Ramsdale. If we implement a controlling, possession-based style with the help of Onana in goal, we will also concede much fewer chances, which will obviously reduce the importance of his shot-stopping abilities.
Mazraoui & de Ligt - I haven't declared them successes, in fact I think both signings involve a fair amount of risk, but at the same time, I believe that for the fees quoted, both of them are worth the gamble. What I meant by them being "quality players" is based on what they showed at Ajax, Juventus, and Bayern Munich over the past 6 seasons. Them not considered good enough by Bayern is also just simply not true, sorry.
Antony - I think he is objectively the worst signing in our history, simply because we paid £81m for a player whose real market value is around £25m. However, I don't think the blame can lie solely with ten Hag on this, as the club was working with a relatively small transfer budget of around £120m in the summer of 2022, up until the opening two defeats in the Premier League vs Brighton and Brentford, which led to the Glazers getting involved in our transfer dealings, and assigning more funds to be spent on incomings out of panic, which led to the arrivals of Casemiro and Antony for big money. This info all comes from the Athletic, so I think we can treat them as facts. If the manager, Murtough, Arnold, scouting department, etc. so everyone involved in our recruitment knew that we could, and will spend close to £250m in the end that summer instead of the original ~£120m budget, it would've likely been a totally different summer with different incomings. So don't get me wrong, ten Hag could've stopped the signing, but everyone was desperate, and in the end I think most of the fault lies with the Glazers. They initially wanted to cheap out, then got involved out of panic after two bad results, and decided to pay more than three times the real market value for Antony, and sign a 30 year old midfielder for 60 million in Casemiro.