From the Article:
The defense official, who insisted on anonymity because formal announcements are still pending, said that Bush wants to replace Abizaid with Adm. William Fallon, the top U.S. commander in the Pacific and that Casey's replacement would be Army Lt. Gen. David Petraeus, who headed the effort to train Iraqi security forces.
Not sure where this sits with Frank, but these individuals were not on his list of recommended replacements. I would guess that if a tank commander isn't a good fit for insurgent fighting, an Admiral isn't going to be much better. At least Petraeus has direct experience with the Iraqi forces and their culture.
I'm sure that we will hear from Frank on this.