What warrior has 20% block in ICC? I have ~ 40% avoidance (miss/dodge/parry) and ~ 13% block (I guess it would be 16% if I spec'd 5/5 SS instead of 2/5). Based on this numbers you'd only block about 21% of the hits that connect. Shield Block's uptime also isn't 50% if you use it on cooldown, it's closer to 33% (up for 10 seconds every 30). Granted your math when it is up is correct (since it ceases to be RNG) but I think you're over valuing it some.
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