I've heard in some interview that Babar asked Ramiz Raja for Fakhar, Sarfraz and one other player (Malik?) in the WC to which Ramiz said ok you can have them but get me results.
My guess is that since Fakhar is normally an opener he has not been doing well at #3 but has been kept just in case Babar or Rizwan are out early in the game (<5 overs). Since that has not happened yet that's probably why Fakhar hasn't done that well. My guess is he's the "backup" opener.