well you should ask your scout (who should be Jericho
(36689)) and also the next U21 manager (the one that will be in charge when Mariotti is 20-21 yo...).
my opinion is that you training plan could be ok. probably 2 levels in PA/HD/DR are already ok, and then some more defense is needed, atleast one level.
but really, ask the scout for any doubts, he knows better than me what are the plan for the younger generations :)