Resto understanding...

[Arkpit 101]

EDIT: The mystery, by the looks of it seems to be nothing but a direct connection to the overhealing when investigating even further comparing many logs and bosses.

I've got a very bothersom issue where I don't understand why my average Healing Wave cast is so much lower than many others which I'll show in the links to compare below:

Links comparing Skorpyron HC between myself and Keehn (running same build):

Me: https://www.warcraftlogs.com/reports/hTtbyQFznGYqCfXN#fight=1&type=healing&source=13
Keehn: https://www.warcraftlogs.com/reports/hwPQHfAz3k28gTjp#fight=4&type=healing&source=35

My armory: http://eu.battle.net/wow/en/character/magtheridon/Arkpit/simple
Keehn armory: http://eu.battle.net/wow/en/character/sylvanas/Keehn/simple

I want to focus on the insane difference in the Healing Wave average cast. It's over double than mine. The difference in gear just doesn't add up for me. 

2k int difference, he got the boots legendary that gives extra 10%, he got a relic that gives it additional 15% and the mastery is bit higher but given all of those things I still don't understand how this works.

I know how our Mastery works but we are talking average cast through 50 in the same fight doing the same amount of casts of all the other abilities as well. It's been bothering me so much these past days that I cannot figure out how my average casts on Healing Wave is literally half on average.

Any help to sorting out this mystery would be greatly appreciated <3

Edited March 16, 2017 by Arkpit

[Arkpit 101]

Also let's add to the mystery because Keehn does have 15% extra effective mastery looking at at 50% hp target and the int difference is providing 10-15% so in the end his bonuses compared to mine is:
15%(relic)+15%(int)+10%(legendary)+15%(mastery)

This is btw still not double value from my average which is very strange to me still but take another example here:
Blowmyface logs: https://www.warcraftlogs.com/reports/rMmLZRK2d8XBcz7x#fight=5&type=healing&source=33
Armory: http://eu.battle.net/wow/en/character/tarren-mill/Blowmymace/simple

Again, look at the near double value of Healing Wave from mine but this time he doesn't have the 10% from legendary boots and his mastery is only 7% up from mine. He even has a less average on the crit for the Healing Wave.

I am so confused and frustrated over these numbers. Even my mastery doesn't make sense since if a target is at 50% hp my mastery gain is roughly 45%, taking my base Healing Wave on my int 216 x 1,45 = 313 and not even close to this which to me is just plain crazy.
I'm healing low targets with the spell all the time I feel.