you still can train player to news roles or special ability on PC version of top eleven !
But on top eleven 2015 mobile app you should be able to do this in a very next future ! I think in less than two weeks there will be an update for this !
Also a friend of mine tell me that if you have began a special ability on PC version and if you haven't made a choice in top eleven 2015 mobile app for assigning skills in one of the three sectors ( defense , attack and physical ) the skill will be auto assign on the special ability but you will don't see it on mobile version only on PC version ! He has made the test and confirm me !