1% of Resilience will reduce the chance to be critically hit by 1%, reduce the damage taken from crits by 2.2% (improved from 2% in Patch 3.0.3), reduce the damage done by DoTs by 1%, and reduce the amount drained by mana draining effects by 1%. While there is no limit to the reduction in critical hit chance, the damage taken from critical strikes can only be reduced by a maximum of 33% (up from 25% in The Burning Crusade). This means that 15% of Resilience is the optimum number and any more points invested in Resilience rating past that point will be inefficient.
Here's the kicker, though. While it only took a mere 39.4 Resilience rating per 1% at Level 70, and because the damage reduction was capped at 25%, players only needed 12.5% Resilience or 492.5 Resilience rating to hit the so-called Resilience cap. At Level 80, however, the rating required per 1% of Resilience is 82. With the new damage reduction capped at 33% and each point of Resilience reducing critical strike damage by 2.2%, this means the new Resilience cap is at a staggering 1,230.
There isn't even enough Resilience in the game to reach that, even if you were equipped with full Deadly Gladiator items and fully enchant and gem for it even with three Jewelcrafter-only Mystic Dragon's Eyes. Even if you apply head and shoulder enchants with Resilience or ignore socket bonuses to put Mystic Autumn's Glows, you would still only barely break 900 Resilience rating. And that would be gimping your damage or healing considerably.
This means that we have a lot to look forward to in terms of gear improvement as the Arena or PvP seasons progress. Blizzard is leaving itself a lot of wiggle room to create more Resilience-laden gear and that means it will take a while before we see the full Resilience on Resilience PvP that Blizzard expects. The dominance of burst damage will be around for a while, as players slowly accumulate the Resilience needed to survive more than a couple of hits. Eventually, that magic number of 1,230 will be attainable and PvP matches will take their proper sweet time.
Arthas awaits and so do your questions. Find the answers you've been looking for that will help you with your journey into Northrend and to level 80 with Wrath 101.