My opinion on stopping hordes is to counter punch. That is, hit their ords, troops and hangars along the front. With a nod to the ‘Fun Police,’ sinking a horde’s cv is a quick way to stop them. I’ve given up on fighter sweeps, though, a good squad should be able to disrupt the horde conveyor belt that usually develops.
How to stop a horde? Is it even possible?
The problem with the counter stroke is that the saying "the best defense is a good offense" is often taken to be true regardless of the situation and circumstances. You need to be able to tell when you're fighting out of your weight, and start focusing on loosing ground as slow as possible, IMO. Attacking without a clear plan, or in piecemeal just makes it easier to be stopped, which seems to happen a lot in the MA's. There also seems to be a lot of this happening:
"alright, fighter sweep to defend A*** begins in 10 mins, join up."
"System: A*** has been captured by the *attacking chess piece*"
"aw crap, they got it. Nice job *defending chess piece*, real great defense there. mission to retake A*** rolls in 15 mins, join up"
What I feel works best for stopping the hoards is an imediate and direct counter punch. Get as many La-7's, 190D's, and P-51's as you can to up, and hurl them at the opposing hoard. The further from your base you can start to inflict noticiable losses, the better. Many will see its going to turn into a fight, and go find a place where they can sneak a base, or put a cap on it. Unfortunatly, this is also true for your side. If it looks like they will have to fight like hell to have even a prayer of keeping the base, many will leave.
Just my $0.02.