Agree with the OP. Mirallas instantly sprang to mind when I saw the tagline. We all know he had moments of brilliance last year as well as matches where he completely disappeared. I think he will be more consistant under RM and expect to see some more jaw dropping plays from him next year.
I guess the above should have been qualified with the statement that he won't see the most overall improvement (think that'll be Barkley), but I think the quality he will gain will be most noted.