~Snip
Yes Rashford is good enough to play for Barcelona but with the present Barcelona's squad I don't think Rashford is good enough to earn a stating role in the Barcelona's team.
This would be a different pattern of football than the one Rashford has been used to but he has the pace and ability to do just fine, I don't think Barcelona will use the buy option later, Rashford future will just be a decent premier league team, but I wish him all the best at Barcelona and I hope he proves me wrong.
I don't know Barcelona's reason for signing Rashford, but Hansi Flick certainly has a good reason. Rashford could be a good replacement for Raphinha if he isn't at his best next season. Raphinha, who often plays as a left winger, plays in the same position as Rashford, but I don't think there's been any confirmation of his signing yet.
Hansi Flick could also play Rashford as a center-forward besides Lewandowski. Lewandowski is getting older and sometimes needs more rest to get back to his best condition during a busy schedule. Hansi Flick knows what Rashford has and what to expect from him, but I'm still waiting to see if this transfer actually happens.