Rashford is not a world class potential striker though, he has shown capabilities of lacking finishing instincts. His movement is extremely poor for a professional, he often runs himself into occupied spaces, plays with his head down, doesn't interlink the play well enough. Solskjaer has even mentioned the conversations he's had with Marcus regarding his positioning, temperament and poise. The only aspect that is keeping Rashford in the aura of the starting 11 is his work rate, if Martial had the same application in his approach Rashford would be on the bench.
I'll always reiterate the same opinion if Rashford is Ole's main no 9 over 2 seasons it will cost him his job. The difference with Lukaku is his contribution is poor but he offers goals, his numbers are at most consistent.
People who turn down Icardi but welcome Piatek it's backwards thinking, they offer the same attributes fox in the box, poacher the benefit with Icardi he's been consistent over a period of time as opposed to one season.