Don't know what has happened to the arena, but now it's f****d!

I have heroes with maxed skills, artifacts, masteries etc with over 164k team power, but now I can barely beat anyone, I'm losing to teams with less than 80k power and everyone seems to have ridiculously powerful legendary heroes that can't be killed.

I can select defensive teams that are almost exact copies of some of these teams and I get killed over and over again. WTF is going on? 

I attack some teams and do not get a chance, just get killed instantly, this cannot be right. 

You've ruined the game and I think it's time for me to leave. I've invested loads of time and money but now all my heroes seem useless. 

Really pissing me off!!