Is the defense commander buff broken, or are defense emblems broken?

I have a heavy with 200+ armor with emblems equipped. With her skill up which gives her like an additional 30% armor she still takes some damage from enemy attacks.

Meanwhile my tanks with around 80 defense, take 1s from the same enemies with the commander defense circle.

The circle says it just increases armor by 75%, but is that really the case? No matter how I look at it, my low defense tanks should be taking more damage than my heavy even if they have the defense circle on them since a 75% increase of 80 is still far less than 200+.