Moved from the NBA Live 10 section. Please post in the correct section regardless of the level of activity, thanks.
The short answer is, you can't. NBA Live's simulation engine, which controls all the stats and results that occur during simulation, is in a definite need of an overhaul and has been for a couple of years now (hopefully we get it in NBA Live 11, now that the gameplay has improved). The rotation screen is your best bet and if you still can't get results you're satisfied with then unfortunately you're pretty much stuck.
Parker for Nash and Shaq is a crazy trade, it's not often you can get the CPU to agree to a deal like that.
I believe Smith's development potential is still pretty good, though I don't know the exact value as it's a hidden attribute and we can't view hidden values on the consoles the same way we can open up the databases for the PC versions.