In all honesty, no one wants to operate this way but that's the reality of it. Player recruitment and selection isn't a science, I don't even know if you can call it an art. It's a judgement call at a point in time dependent on what player is available at what price. Clubs have to do their due diligence but ultimately every signing is a gamble. No one knows how any player is going to turn out until he's wearing your shirt.
If we were to look objectively at any top club you would find players bought, tried, judged not good enough and moved on. Just look at one of the most successful managers of the Prem era, Ferguson, how many duds did he buy in his time? Loads. But no one batted an eyelid because ultimately it didn't matter. He delivered success on the pitch which paid for everything, mistakes and all.
I don't want to insult anyone here but City as a club has moved on to bigger things, the fans need to move on with them.