Yes, plenty of average players can have good seasons. It happens all the time. It’s also much easier to look good in Italy than it is in England. Especially for a player with such obvious physical deficiencies as Zirkzee. And respectfully we’re talking about a Bologna side who finished 5th in Serie A. It’s a world away from playing, and being good enough, for Manchester United. And if that top coach that you mentioned rated him that highly, he would have taken him to Juventus with him.
Currently the likes Moises Kean, Adama Lookman & Christian Pulicic are amongst the top scorers in Italy right now, would you call any of them good enough for United?