I think ever since its been introduced, I haven't got anything good from it. The few proc I have got were always on the same piece. ;-)
I had a streak in Legion, where my chest item was also ilevel 960. Didn't get a proc for six months!
Even now, still almost none.
Whatever.
It is, what it is.
A lottery loot system. Slot machine 101.
If you are lucky, you get a sweet piece, otherwise, you get what you "deserve."
In other words, if you want 380 gear, you better do 10+ mythic keys or mythic raid.
Anything beyond that is just a bonus. Enjoy it, if you get it. But, don't hate.
Do I like they "loot system?" I am pretty ambivalent.
If I get 325, 340, 365, 375, 395, 666, or 999 gear, I don't really care.
At a bare minimum you get what you deserve.
But, you nor anyone else earns a TF piece. It's just a gift, beyond what was earned. Enjoy it, let people enjoy theirs.
No one does a heroic raid, and gets 235 lvl gear. You always get the minimum of what you deserve.