I'm still waiting as well--and I ordered Monday. I guess it's just my personal opinion. UPS Ground is more reliable, more secure, and provides more tracking information, so there are trade-offs. But given that they are the base shipping options for their respective carriers, they are comparable options.
My guess is that the large volume of orders during the Reverse Sale forced them to use two carriers. Some companies have certain contracts with carriers allowing them to send so many packages. Overages occasionally have to be sent via an alternative carrier.
Just a thought. I'm trying to remain patient.