The bolded part is simply not true for every situation though.
He doesn't have to up his shot ratio if he is scoring as per his expected goals which he has been for the past two seasons.
What's the point in a striker having a shot twenty yards out where he has an easy pass instead, this is where stats have no context.
You can't just say he has to improve his shot ratio as that doesn't equate to every striker and every situation. It's far too simplistic.
The context here is where Hojlund plays, he very rarely moves from the middle during games, he is a focal point of attacks and will often drop deep to pick up the ball then move into the box to get on the end of through balls or crosses, he very rarely has shots from outside the box as he would rather score the easier goal, also he is very good in the air.
As far as I am concerned he will be utilised very similar in United colours, so his shot ratio doesn't need to improve as United on average create way more goalscoring chances than Atalanta per game, so by proxy his figures will naturally be higher anyhow across the board, assuming he has a positive impact of course.