If I remember correctly, it is Larian's intention to make the strategy game relevant during the RTS game, and there has been some discussion on that subject (including my stated preference for strong restrictions on unit production during RTS). I agree that the RTS battle still goes far in negating the initial advantage you have.
I have noticed that one battle forge can beat quite a few hunters if they're just stationed near it to end the enemy. So if I send 4-5 hunters to finish the last standing battleforge and concentrate on the big battle on the other end I may well find that base reconstructed and my hunters gone. While this may be to my shame, it still indicates that strategy units are only there because somebody has to start the battle and grab the first sites.
That's not what we're discussing here, though. The autoresolve is also bonkers. (Which is more easily discussed because the numbers are there on the screen, and the tests run rather quickly.)
The victory probability for autoresolve appears to be a very simple proportionality: Your chance of winning = your force's share of the power on the battlefield. Which leads to one trooper versus 4 having 20% chance of winning instead of a more realistic 6% (realistic given that it is allowed to fight enemies one by one and takes no damage from the enemies it defeats).
For 1v4 to give 20% overall, the lone trooper's probability against each individual enemy would have to be just below 67%. In other words, troopers are ninjas. (This number is probably a little off. I'll put in a more accurat one if I produce a more accurate test case.)
1 trooper with 1 star
versus
3 troopers with no stars
1 hunter with 1 star
1 armor with 1 star
Let us give the trooper with a star 2/3 chance against a trooper with no star. That's generous, no?
Then to defeat all the troopers who kindly attack one at a time, it would have to succeed at (2*2*2) / (3*3*3) odds, 8/27.
Then, to err once more on the side of generosity, let's assume 50% chance against hunter with one star and armor with 1 star... Bear with me.
Odds to proceed to defeat them as well would be: 1/4
Odds overall would be: (8*1) / (27 * 4)
That's 8 of more than 100, which is less than 8%.
Giving the one trooper 8% chance of winning would therefore be super-generous. (8/108 is about 7,4% and to reach that number I simply assumed that hunters and armors have no advantage over troopers.)
The trooper got 13% chance of winning, and took out the hunter before it died.