Xavi has improved Barcelona there is no doubt. I wonder why he is not getting credit for that, just that he is not lucky or he is not experienced in the Europe competitions. Apart from that Barcelona is doing well and this is seen as they are topping the laliga table with 8 points clear and I am hopeful that Barcelona will become the champions of Laliga but being able to beat Manchester United I'm old Trafford, I am not sure.
Xavi has really improved Barcelona since he became coach of Barcelona, the difference in Barcelona performance is clear which show the team is in the best state compare to how Barcelona used to be two seasons ago. The Barcelona and Manchester United game is unpredictable, it can be any of the team that will win the match.