Well u got nice ammount of matches tbh for that rating, 253 games. You are not playing underpowered 2s setup eaither, nor is your gear bad - i suppose u started season with donor wep allready.
I started in crafted gear/no donor **** on any of us and me no previous experience on shaman what so ever and we r 60ish matches less than you with 20ish rating difference.
I mean not trying to make you look worse or anything, but there are obvious lots of good/better players in top 5% or so. Bottom line is, PvP scene is good enough to have some simple fun, w.o sacrificing other aspects of the game, else insta pvp server is far superior to Molten as its meant to be.
About ur other part of the post, you couldnt be more right. There are few op bugs but its not Moltens fault or expansion, its 2s itself thats broken since s3. Moltens fault is that they r not promoting 3s in better way.
On my previous server, far worse to molten in any way except 3s/5s scene, they promoted 3s by simply giving titles/rewards only to 3s and rank1 5s, made ppl play 2s only for gear and 3s for rating, and it was by far most fun i had in this game, uncomparable to Molten in any way.