Except that distinguishing between a simple appearances figure and actual minutes played is extremely relevant, as the other poster pointed out to you. It becomes even sillier when you're comparing Van Nistelrooy's goals-to-appearances with two players who joined the first team aged 18 and 20 and haven't played as strikers for the majority of their career so far.
Again, apart from the clear evidence that they have been improving season on season, up until Martial's regression so far this season.
If they played for another club and had put in the performances they did for United last season, this place would be crying out for both of them. Just look at the hard-on everyone has for Grealish, a player two years older than Rashford who's just about edging him performance-wise for the first time in their careers this year.