Rashford simply needs to play according to the coach's instructions when he's deployed in his preferred position, as the Barcelona coach will then assess Rashford's level of cooperation with his teammates. Barcelona is currently striving to make significant improvements in order to have a better season and free itself from financial difficulties, so Barcelona should be able to win several major competitions next season. And Rashford's arrival at Barcelona could at least add a little strength that could have a positive effect on the team as a whole.
In a match, every player must follow the coach's instructions because they have carefully prepared their strategy. However, Rashford's problem goes beyond that; he needs to train harder, especially improving his individual skills and working well with his teammates. Rashford's arrival at Barcelona provides more space, as the coach has the opportunity to rotate players if desired, given the busy match schedule next season. Rashford's abilities are also excellent when he's in top form, which is an advantage for Barcelona.
This will not be easy for Rashford, with many competitors to get playing minutes, Rashford must be able to take advantage of small moments to be able to perform optimally and make an impression on Hansi Flick, even though it is difficult, I think Rashford still has the possibility to do it because Barcelona is a team that is developing now so Rashford has the possibility to improve his career if he can achieve and contribute to the Barceona team.