The theory that makes the most sense to me comes fromt Doug Dineley, InfoWorld's Test Center director: Android tablets aren't competing with iPads, but with laptops and netbooks.

via <a href="http://www.infoworld.com/d/mobile-technology/the-android-conundrum-why-tablets-tank-smartphones-surge-165?page=0,1">The Android conundrum: Why tablets tank, smartphones surge | Mobile Technology - InfoWorld</a>.