Im not the expert here but my take on it is that the final select is a review and approval of all aspects of your application. Meaning, they review medical, fitness, board recommendation, any special circumstances involved. While it seems like the Professional Recommendations are really what counts and the final select is all but "automatic" as long as everything else is clean, you could technically be refused and not receive a final select based on... pretty much whatever reason they come up with...
Can anyone clarify what exactly the final select process reviews in determining which applicants get selected and which don't? would be interesting to get some input on that.