Given that you have a couple young PGs, I'm guessing you're training them, which means you'll have to buy veteran bigs if you want to improve quickly. Based on the game ratings, that seems to be your team's weaker side. Even if you don't play an inside offense, most other teams will, so having bigs who can defend is essential. Also, a team that is balanced in skills won't be balanced in salaries; bigs just cost more in this game. My opinion, expand the arena until you can afford to add a center with ~14/15 ID.
(female dogs in heat).
Then go after Kobe. *Wink* *Wink*