Well I was under the impression he was 2 position training 6 players, maybe I'm wrong but that is the impression I got from his original post. I was assuming that the height of the other guys he was training were high as well. His income from his arena would allow him to purchase some older but still good point guards and shooting guards. His remaining 6 players could be trained in the C/PF positions to improve his team from that aspect. Then at the end of the season (I'm assuming the players are all young) the salaries won't have increased that much and he will have 6 decent C/PF players and still have his older guards that will be good. Also he will be accumulating money from his arena in the mean time. I think this would be enough to promote in div 4.
To answer your last question, I see his team improving by having 6 big men (3 Cs and 3PFs) plus his older guards (that aren't suberb but good enough for a league filled with bots).