Honey Badger
OG
The only contribution your gear will make to your overall power is through a small modifier based on your average item level. For every point that your average item level increases, your pre-determined PvP stats will increase by 0.1%. That means a 25 item level difference between two players only results in a 2.5% difference in stats, compared to the 25% difference it makes today. There’s still a little incentive to improve your gear – a concept we think is important for World of Warcraft – but the benefits are much less
Twinking has always been about having best in slot gear. Not so much skill, but how your toon is gear. As of right now there is no Bis so much it's about play style how you hear your toon. With legion having a high item level gear goes back to twinking days of having BIS gear.
The example you use is 25 item level difference between 2 players only results in a 2.5% difference in stats. 5k ferocious bite with 2.5% unless my math is wrong is dishing out 250 damage resulting in a 5,250 ferocious bite. Meaning, IMO grinding for gear is back. Play style is out and gearing BIS is back in Legion.
Only time & PTR will tell.