It looks Barcelona is targeting Marcus Rashford because they need attacker who can play effectively in many positions which he can do as  left right or central forward. This flexibility is very valuable as it gives coach more options to change tactics during games. And loan with buy option like one rumored for Rashford is smart financial move for Barcelona because it lets them try him out without big cost reducing their risk if he does not fit while still allowing them to sign him permanently if he performs well.