It wasn't all Mac though. It was also an unfounded belief in what some of our new "wonder weapons" could accomplish. Particularly the B-17 but also a force of modern submarines. Stimson and others held a view that even a relatively small number of B-17s could have a significant impact in the Far East. Similar to Churchill's view of what a couple of modern capital ships at Singapore could do. Obviously they were wrong but people were drinking that Kool Aid by the gallon in 1941.
I still see Mac as central in this, the thoughts of the others would have gone nowhere were the PI Army CoS not behind it. This is not to say another would not have gone the same route, but at this point my take is most of the candidates for the job would have been less optimistic than Mac.
There is the long shot possibility the preparation effort could have started sooner, or been more rapid. Having the forces in place i Dec 41 that were intended in April 42 would damage the Japanese offensive.