I understand you being drawn in, we were all bad asses.
As for the waitlist, I believe last year more were taken off it than the year before (although not by too much). It was probably due to last year being the first year for OOS applicants. I would predict this year will probably match last year in terms of waitlist movement. Also, as far as I remember, last year Phoenix and Tucson made acceptances separately, so that's no different this year. However, even though they do things separately there is a lot of overlap as you'd imagine with a couple hundred AZ applicants vying for over a hundred IS spots. Maybe some one out there knows the percent of applicants accepted to both campuses, but I don't. I would have to guess that if you only include applicants accepted BEFORE the waitlist you'd see a very, very high percentage of overlap. Since obviously we can only go to one campus, this leads to a lot of spots being vacated for the waitlist. The other thing is that many people taken off the waitlist choose to go elsewhere, so its not like 70 of 115 are WL. Those 70 WL spots may be for only 20 spots (just picking a random number).
It makes sense for Tucson to do this. As a state school with lots of budget issues, the last thing they wanna do is over-accept and have too many people matriculate. When I interviewed at Pitt last year they said the second year class had that problem where not enough people withdrew and they were stuck with a huge class (which says a lot considering I think they're already over 200 to begin with).