Nope, no public stats.
Even if there were, it would be difficult to extrapolate the figures and apply them to our own requests in any meaningful manner. For instance, even if DVC tells us that the overall success rate is 70%, that doesn't mean a whole lot for a member trying to get AKV Concierge for Christmas week. I can safely say the odds of getting such a room off the waitlist are significantly less than 70% (or whatever the true average might be.)
IMO, the most relevant factors would be:
1. How far out did you get on the waitlist? DVC won't/can't tell you where you stand. But since waitlist requests are processed FIFO, it stands to reason that the earlier you get on the list the better.
2. How many nights are you seeking? Most waitlist requests are met as a result of another member canceling. And if a cancellation doesn't meet your request exactly, you get bypassed. The odds of getting 2 nights are therefore higher than someone seeking 14 consecutive nights.
3. How many units match you request? Trying to get an Old Key West Grand Villa around Christmas (there are only 27) or AKV Concierge (there are only 5) for New Year's will not yield a high degree of success.
We've probably done the waitlist 5 times and every time we got something. Now that goes back to the days when members could have unlimited requests so I'm not saying that we got our top choice every time. I remember one time we waitlisted for all 3 categories at the BoardWalk and ended up getting the Pool/Garden View. No Standard or BoardWalk, though.