Perhaps if you forget such “minor” thing as the core of the entire hero talent.
Improving lunar to be a 30s CD AoE increasing mastery by 30% Leech by 10% healing for about 5m+ and however much it converts from its damage since its arcane.
It also converts one of our main abilities into arcane, so they benefit from arcane heal.
To a minor extent, free rage from all the moonfire procs. Can never overlook those on pull.
You’d have to do content over LFR where mobs actually hurt to appreciate it.
That or rotation and or gear is poor and not really seeing the numbers.
Are you using it out of form? did you forget to equip half your gear?
Are you sure your guardian is lv 80?
Also, I think you forget mastery doesn’t only increase the health pool.
I am not sure what kind of content you are doing but even in low keys (and by that I mean higher than any you’ve done) the healing from Mastery, and Elune’s favored are up there. (yes, mastery proccing from arcane, from an arcane AoE that increases mastery)
This one takes the cake though. Keep guessing! Bound to not be entirely wrong sooner or later, broken clock yada yada