The youngsters aren't considered as cover because by and large since Benitez has been at Liverpool the youngsters are nowhere near good enough to get in the first team, and have shown that when called upon they are totally out of their depth, hence the whole raft of players he has brought in to get used to his methods and systems. In a league as tight as the Premiership is a couple of bad results brought on by playing these types of players will end up costing a Champions League spot.