How does static damage reduction work? Math

With something like the Aegis of the Deep azerite essence, and guardian druid’s Brambles, that reduce damage taken by a flat amount. I assumed it would work before armor and just remove part of the damage, so that if weak enemies were hitting you you’d take no damage at all.

If I go outside boralus and get attacked by a fox that hits me for 2200 physical damage (no armor), and use Aegis of the Deep (Take 4400 less damage) the fox now hits me for about ~1300 physical damage. Which doesn’t fit at all for how I thought it worked.

Someone mind explaining how the math works for it?

Aegis of the deep reduces the original amount.

Lets say that you have 50% damage reduction from armor.
Aegis reduces the damage by 4400.

you get hit by a 10000 damage physical attack.

First it is reduced by Aegis 10,000 - 4400 = 5600
Then it gets reduced by armor 5600 * .5 = 2550
then it gets reduced by block.

So if an attack hits for 100k it gets reduced first by 4400 reducing the initial damage to 95600, then by armor down to just under 50k. Making Aegis roughly a 1-3% damage reduction activated ability. Of course this is going to vary based on pull size and how much the damage the attack does. It’s just that when you need the mitigation it’s not going to provide enough to matter.