My armor percentage right now is 85% (It's a singleton run), but the actual damage I'm taking seems to be about 25% of the attack damage or more. For example, an attack did 126 points total of physical damage, and I blocked 91 points and took 35. This is about average based on looking at a number of example attacks on my character. Why aren't I taking around 15% of the damage, instead of 25+? Additionally, there seems to be pretty big variance, with some attacks being reduced by around only 66%. Note that I'm playing on Torment, and I'm not sure how that affects this issue.
The issue is even more prevalent with my other defensive stats which are lower: for example, my cold resist is sitting at 71%, but the damage I take seems to be around 60% of the attack damage, not ~30.