You can get the rookies by playing " Lock Out Mode " , where by you play out an entire season negotiating with GMs , after which you will be asked to purchase the game again .... Then said players will be available . Good luck .
go to your 2k share on 2k12. i was going to explain the whole process but i rather show you a video from my favorite youtube commentator blinkfro and they have their actual faces and everything. There are some minor negatives though he will explain everything in the video