Originally Posted by LawrenceOfTennis
He's not that young anymore. Should start playing futures and quit juniors as soon as possible. Playing other 16-17-18 year olds will not make him a better player. Look at Tomic: only a year older and already top 50.
There are other considerations: potential sponsorship, management deals, current sponsors, confidence, strength (body type)compared to peers/opponents, potential for injury.
A lot of the top players played ITF Juniors - Federer, Roddick, Monfils, etc. - the list is extensive, whilst a few very talented/gifted/stronger player have managed to short-circuit the system and gone straight to the top at a young age (Djokovic, Murray, Nadal, Tomic, etc.).
When the time is right Saville can step up. My opinion is that Saville is not ready for the stronger senior game yet. He should play a high level mix next year - only the Slams in the Juniors (whilst his ranking allows) and a limited number of senior tournaments.