What "Legion gear" are you talking about? I just renewed sub, and I'm assuming I missed out on a ton of stuff. Are you saying that if I "missed out" on it, I'll never be BiS?
Yeah man, during the pre-release of Legion there were several "Invasion" events that took place in zones like Northern Barrens, Westfall, Hillsbrad, etc.
By entering the zone, Horde and Alliance players alike would clear 4 Stages together. The first and third stages were clearing Legion mobs that spawned in the zone, the third and fourth stages involved slaying Legion boss mobs.
At the end of the second and fourth stages, players who were in the zone received a chest item, which contained geared scaled to their characters level (all of the mobs in the zones scaled to your level as well, meaning any level eligible to do the invasions could participate in the effort until the end of Stage 4).
The gear contained in those chests were blue fel-gear, however if you were lucky the chest would proc and you'd received a Warforged or Titanforged version of the piece of gear you got.
The fel-gear item levels are as follows:
Normal blue: item level 24
Warforged blue: item level 29
Titanforged blue (it will still display as "Warforged" next to the item): item level 34
TL;DR
You could AFK in the zones or participate for the 2nd stage and 4th stage chests to try and get pieces of the item level 34 gear (the PVE stats on it are superior to BoA and other pre-BiS gear before invasions) which, in turn, was the best in slot for Battlegrounds since BG stats scale off of your characters item level now, instead of actual equipment stats/enchants.
This gives players who have full Warforged gear a significant advantage in PVE, and a slight advantage in BG stats as well.
There's no other way to obtain the fel-gear anymore as of this moment.
Hope that helps fam.