I don't know how he's going to do at United. Nobody has a clue how anybody will do. I don't want Qatar for a multitude of reasons, of course the ethical reasons but also the business ineptitude reasons.
My point is - it takes a long time for an owner to have a true impact. Unless they are being a sugar daddy (which I disagree with from a sporting competitiveness/equality POV), then it's going to take time to make their mark. They aren't coaching the team, they aren't playing the games. They aren't scouting players. They aren't/shouldn't be identifying signings. They have to make the right structure and hire the right people to be in charge of these structures, and then allocate the appropriate amount of money to support team needs, meeting targets that they set, while not putting the club at risk. That's what a good owner needs to do. That's takes years to judge. You can see if somebody is being a sugar daddy/don't care about losses right away or if they're being incredibly dumb right away (Glazers), most others are a big grey area until a significant amount of time passes.