Player quality is the biggest problem with EU, the issue is instead of fixing it the good players just move to US and make it worse. Can't fault them for it, but it is unfortunate that we can't keep both ecosystems going at the same level. A lot of the Legion Twinks still remain (And aren't looking likely to learn how to objectively / awarely play WSG), and even in WoD the quality of EU games was definitely lower than US. I'd let the dust settle, let the new guys learn how much they have to learn (And decide if they wanna learn it), and hopefully there won't be a mass EU exodus before the game quality starts going up.
Yeah lock just doesn't have the oomph it had in WoD (Can't comment on Legion). Because of the way MM's damage functions, it's kinda taken the old destro warlock role and merged it with the WoD SV hunter role. If you want a caster who pumps high sustained single target, has access to CC, and is also made of absolute fucking paper, then your best bet would be mage.
EDIT: Just do the whole bracket a favour and don't just play arcane.
