If a Powell-Gates-Petraeus trio ran the show from the beginning...

[cannonia]

Maybe better?

The real problem is what we see at the beginning of every war, the peacetime army.  So many parts of the system, from promotion boards to procurement policies to "up or out", hurt the morale or effectiveness of the armed forces (usually to the benefit of someone on the inside).

Gates would have spent his first few years doing the same thing that Rumsfeld did: fighting with generals while trying to modernize the military.  During peacetime, generals get their jobs because they are good politicians, not because they have real military experience.

Rumsfeld's ideas for the military were great for Afghanistan: small elite units working with the locals to achieve results.  The introduction of "regular army" tactics and bureaucracy screwed things up there immensely.

Petraeus knows counterinsurgency.  That would have been a boon to have from the start of the Iraq war.  Also, having one commander throughout the operation would have helped tremendously.  Tommy Franks caused a lot of the problems in Iraq by setting his retirement date and not planning for anything past that day.  But would Petraeus have had the clout to fix what was broken in this scenario?  As is, we've been blooded and Petraeus was put there to make things better.  Had he been there from the beginning, could he have achieved the same results?