Reduced Flask Charges Used mod improperly considers best roll

I'm not sure if this is by design or not but the mod on belt "(20-10)% reduced flask charges used" is taking 10% as the "best" roll even though 20% is the most desirable.

I was using the rog crafting options that roll values multiple times to and keep best and it returned 10 multiple times instead of closer to 20. I'm assuming this is because this is an inverted stat and it's just trying to roll the value closest to positive