I would be willing to bet that a lot of the "stolen" pots at nisqually are actually lost pots. I speak from experience, and watched it happen to my pots along with about 20 others this year on the opener. The tide really rips off the flat, and within about 10 or 15 minutes all the pots went from bouys floating nicely to gone. I came back at the slack at daylight, and there were 4 or 5 pots left where there were 20 some at dark. Unless everyone pulled them in the dark, they got washed away. I'm sure the pots got pulled right off the shelf.
This isn't to say that pots aren't stolen. I know for a fact some of mine have been picked while I was out there this year, and don't doubt there are plenty of lowlifes who would take someone's pots. Also, if you can't find your pot, don't be afraid to look a hundred or so yards away. Often people float away from were they pulled your pot while they clean you out, and the toss it out when they are done. The end result is your pot moving which ever way the tide was going when they pulled your pot.