In my opinion, anyone who dies to the same boss mechanic several times is underperforming. It's okay to die to mechanics every once in a while (especially in new content), it happens to all of us. BUT if you don't even try to learn from your mistakes and you need a rez every minute while you constantly have the death debuff during the whole fight, then you are underperforming. To me, constantly being dead is worse than an imperfect rotation. Sorry not sorry.