Battles are determined via two separate d100 rolls that are modified based upon the tech of involved units and the number of units.
Are you sure?
That means 100 vs 100 will lead to
0-24 Stalemate = 44% chance
25-44 Victory, Territory Gained = 13.1% *2 chance
45-59 Victory, Territory Gained, 1 Tech Captured = 7.2% *2 chance
60+ Victory, 2 Territory Gained, 1 Tech Captured = 8.2% * 2 chance
Note how the great victory is more likely than good one and both of them combined are more likely than the marginal one.
Now lets give one side minor advantage
d100(A) versus d100+10(B)
60+ Victory(A), 2 Territory Gained, 1 Tech Captured = 4.65% chance
45-59 Victory(A), Territory Gained, 1 Tech Captured = 5.7% chance
25-44 Victory(A), Territory Gained = 11.1%
0-24 Stalemate = 42% chance
25-44 Victory(B), Territory Gained = 15.1%
45-59 Victory(B), Territory Gained, 1 Tech Captured = 8.7%
60+ Victory(B), 2 Territory Gained, 1 Tech Captured = 12.75%
Great victory for team B becomes even more likely, stalemate is still the most likely result
Large advantage
d100 vs d100+25
60+ Victory(A), 2 Territory Gained, 1 Tech Captured = 1.2% chance
45-59 Victory(A), Territory Gained, 1 Tech Captured = 3.45% chance
25-44 Victory(A), Territory Gained = 8.1%
0-24 Stalemate = 36.7% chance
25-44 Victory(B), Territory Gained = 18.1%
45-59 Victory(B), Territory Gained, 1 Tech Captured = 10.95%
60+ Victory(B), 2 Territory Gained, 1 Tech Captured = 21.45%
Note how common 2 territory gained becomes
Huge advantage
d100 vs d100+50
60+ Victory(A), 2 Territory Gained, 1 Tech Captured = impossible
45-59 Victory(A), Territory Gained, 1 Tech Captured = 0.15% chance
25-44 Victory(A), Territory Gained = 3.1%
0-24 Stalemate = 24.25% chance
25-44 Victory(B), Territory Gained = 18.81%
45-59 Victory(B), Territory Gained, 1 Tech Captured = 15.34%
60+ Victory(B), 2 Territory Gained, 1 Tech Captured = 40.95% (doh!)
I don't know how hard it will be to get a +50 advantage, but that looks like a game over.