Take these thoughts for what they're worth...
The LP / PER rubric is way too simplistic for this game. Instead, players should have ratings for finishing at the rim, mid-range jumpers, and perimeter shooting. This would allow the game to more accurately reflect the types of players who actually appear in basketball - the Shane Battiers who only shoot 3s and never shoot mid-range, the Rondos who finish and shoot mid-range but can't hit the 3, etc.
The DEF rating is also too broad. There ought to be a distinction between players who defend on the perimeter vs those who can defend the post. Right now, every high DEF pg is effectively Shawn Marion, because you can use them to defend positions 1-5. In real life, my 5'9" pg would be destroyed by a 7' C. There's no reason the game shouldn't reflect this.
It's too easy to estimate where players are going to end up ratings-wise. In real life, some players end up being busts. And some who were not highly recruited end up breaking out and being stars. One way to handle this might be to inject some variability into the ratings between when a player signs and when he actually shows up on campus. There might be a chance of each rating moving up or down, with big changes being rare but possible. Variability would be higher for freshmen than for upperclass transfers.