We'll never know how things could have been, but I look around every year and you can see teams that make good and bad signings. We needed the vast majority to be good to have any chance of survival. They weren't.
My major problem is that I'm not sure half of them are good enough for promotion in the Championship. Wes, Trez, Engels, Guilbert, Marv, Konsa, Targett, Luiz, Hause. How many of them get into the Leeds/WBA/Brentford sides? Not many.
The uproar you mention would have settled after a game or two when he held the ball up like an actual footballer unlike Wes.
Yeah, never know if Kostic would have settled but he can run and cross and shoot and control and kick the ball so I think he'd have been a big jump up from Trez.
We're incredibly unlikely to get another chance to overhaul the squad to that extent for another 20 years. I can't think of another time in my lifetime it's happened.