The reason Davis has liked zone blocking better than drive blocking is because the defense can't tell the difference as easily between pass and run. Period. I have not liked it either and wanted change, but to be fair, our offense has been awfully hard to stop for quite a while.
As far as drive blocking not working in major college football because of stunts, slants, blah, blah, drive blocking is all over the TV every Saturday of every fall and it's works pretty well alot of the time, talent and various other factors dependent. Granted, not as much on Sundays, but Saturdays, no doubt.