From: The Zone™
And compared to vanilla AE much less support. As an example, in [vanilla] the SW Pacific (aka MacArthur's hordes) gets tons of US Base Forces with lots of support. In DBB you will notice these many base forces filled with lots of support are gone.
As for Air Support they found, in my opinion, a very elegant to deal with this. Instead of abstract base forces you have Base Group engineer units. For example, you have the 11st Bombing Group (3 squadrons). Then you have a 11 Base Group (air support = 72), their support if you want to stay organized. I would say, although this is maybe only an impression, that you have less air support in this mod which makes the whole thing more realistic.
Then you have lots of special engineer units (especially in the SW). Basically few squads which will help to unload ships in beaches or small ports.
And many more things.
Everyone should be playing this mod
P.S.: if anything, I always wondered why the Base Forces (well, at least the ones that are supposed to support the air units) cannot be divided (like divisions). After all, each group has at least 3 squadrons. You don't concentrate them necessarily.
Ah nu cheeki breeki iv damke