PS is flipped from the inside to the outside of a cell wall. It's not flipped from the inside of the tumor to the outside of the tumor. The flipping occurs in both locations for different reasons.
In terms of the quantity of PS flipped per cell, I don't think that's the issue.
The complimentary effects of bavi and docetaxel have been documented (FTM and I have both posted links on the other board). Bavi does a better job on the developing vasculature. Docetaxel does a better job on the necrotic core. Together in combination therapy, they appear to outperform what each has done separately.