What is the math behind Shielding/Defense?

Question

Because shielding is a 'dodge' and incoming damage numbers are so dynamic its hard to determine its value.

There is a formula on the wiki for 'average damage':
https://tibia.fandom.com/wiki/Formulae#Armor_and_Defense

spirit guide

Defense:	17	280.6
Shielding:	32
Armor:	33

shoulder plate + loyalty + blockade

Defense:	26	233.6
Shielding:	39
Armor:	33

mastermind shield + loyalty + blockade

Defense:	37	190.7
Shielding:	39
Armor:	33

And its just hard to digest the accuracy of these numbers.
They also vary wildly based on the gear which makes this question more interesting for me.

Mostly though, average damage seems so disconnected to the idea of dodging.
It also doesn't line up with or use the new Defense value we can see in our character page, a (shield defense) • (shield skill) formula:

Can anyone shed light on how effective Defense really is?
Can we ever get a (defense) • (attack power) = (% to dodge) formula?
Do we need Attack Power values in the cyclopedia for creatures for this to all work?

Comments

Good question but insert your data in the linked question. You can edit the linked question and put more info to be discussed there or even attempt to answer.