Its not like the maths you use are particularly clear, but if you have 50% of your armour, you have the same chance to be affected by cc no matter the values. It's a terrible system because the game is built around the amounts mattering. Loosing a portion of your armour should not make you vulnerable when cc is everywhere and can be applied just by taking a step.
gambling on some rng cc affect is not a deep strategic decision. It's just a sign of gambling addiction.