If Lukaku has as many shots per 90 minutes as Ibrahimovich, whilst maintaining his fitness and his conversion ratio he'd score 35 goals in the Premier League compared with Ibrahimovich's 17.
Obviously it isn't as straight forward as that but on balance do you believe Martial will score more or less than 4 Premier League goals? On balance to you believe that Pogba will score more or less than 5? Likewise Rashford with 5?
My view is if managed correctly those 4 will score 60 goals next season compared with 31 last season.
Is that ridiculously hopeful? Possibly. But if I believed Martial, Pogba and Rashford (as well as Bailly, Pereira, TFM etc) at their age and with their increased experience and with a year under Mourinhos pupilage were only ever going to stand still then we require major surgery - I'm talking a new team and a new manager levels of surgery.