Well, only complete speculation, haha. It seems to me that if you compare Darden's numbers to Duke, which has a similar ranking, the number of waitlisted applicants seems low to me. Duke has about 8% of all applicants on the waitlist and Darden has 3%. However there are other schools with similar percentages as Darden, UCLA also has about 3% waitlisted.
A complete hunch, but I feel like Darden waitlists applicants that could just as easily have been accepted. Then they sort of use the list as a holding tank until they get all of their applications in and they then pull from the waitlist to fine tune their class GPA, GMAT and experience. I feel like bigger classes like Duke just waitlist candidates to ensure they have a backup who will pay full tuition if a candidate drops.
Darden's adcom has been very impressive to me, and I got the feeling that I had some hope after I talked to Cheryl Jones two days ago. I think we have a chance, but I'm always optimistic until I get the rejection letter.