The hard part about waiting, is slowly watching you chances of getting in die. This is how my number-hungry brain interprets it.
UTSW accepts 2/3 of their applicants on pre-match. This means that when we go into interview, we can expect our chances of getting in at around 330 acceptances out of probably 800 interviewees (75 people per day and there are 11 days). This puts your chances of getting in at 41% if you get an interview (this assumes that out of state and mstp are the same as the in state applicants in all ratios).
However, if you do not pre-match, then there are only around 75 slots left open off the wait list. Which means that if you do not pre-match, your chances of getting in are around 75/550 or 13.6%. Thus if you don't make the pre-match, your chances of getting in fall by a factor of 3. Or from around 4 out of 10 to just over 1 out of 10. In other words very bad chances of getting in after the pre-match.
Gotta love the math thinking. Wish it could help with medical school admissions instead of just making me freak out!