I don't have the numbers in front of me, but the rate for "non-select's" going to IDE INRES is much better than SDE which is only 2-3%. Non-selects typically have the best chance in their last look. As a Sq/CC I had two non-selects get picked up and both were in their second look, which at the time was highly unusual. As I recall they are trying to send IDE folks earlier and SDE folks later which may open the door for late look non-selects.
The board/DT looks at your entire record, SURF, and the most importantly...the strat on your 3849. Your Wing/CC usually gets at least one silver bullet that will be honored unless there is something bad in your background. Your individual circumstances will also affect your chances...if you were recently moved out of the squadron to the Grp or Wg, that is usually another message to the board.
Best of luck.