I have absolutely no idea why Asdrubal Cabrera is being left off. By all reports, he already plays ML-caliber defense at short, and he more than held his own as a 19 year old in his first exposure to high-A. Unless I'm missing something, and he's not eligible for Rule 5 selection for whatever reason, then he's a strong candidate to get picked real early.
Update: Nevermind. According to Dave, Cabrera didn't need to be protected after all. Minor disaster averted.
Update #2: J, who rules, and who also knows a ton more about the minor league system than I ever will, has posted his writeup on the whole thing. Go give that a read.