So... how would you fix block?

Its a good idea in theory Ascendant, and it worked in Naxx when bosses wernt hitting terribly hard.
But in Ulduar with 1-2 shotting bosses.
You gotta either have a Schmegload of mitigation, or a serious avoidance nerf to make mitigation worthwhile.

Im in a similar situation to Lightstrike.
My EH/Avoidance set is almost block devoid now.
Only my wrists have block rating & block val (Naxx25 item).
Everything else is Def, dodge, parry, hit or expertise.
My only block is comming from defence and strength. My block rating is 12.6% and blockval a measly 1160.

IMHO this issue with block stems from - oddly enough - avoidance.
Blizz made stacking avoidance too easy. Tanks avoidance got too high too quickly.
eg Naxx25 geared tanks having 60% avoidance.
And because tanks could get that much avoidance so early on, the Ulduar bosses had to hit alot harder to be able to kill a tank and not have trivialised content with immortal tanks (assuming the healers are awake).
The bigger the hits get, the more block sucks.

Here's my suggestion. Remove BV entirely. Reimburse items that had it by increasing their stats by 15% or something. Now, block rating's effectiveness gets cut in half, or quartered- so block cap is impossible or unfeasible. Blocking would reduce the damage of the incoming attack by half of the percentage that your armor reduces attacks by. So, if your armor reduces hits by 60%, your block would reduce a hit by a further 30%. They would obviously have to be applied separately- 60% off the main hit, then 30% off that. That would seem to fix the hard hitting boss problem, and it makes sense- the more armor you have, the more you'd be able to steady your shield or something. The reduction would be capped at 37.5%, because the armor cap is at 75% (most likely nobody could reach that, but just in case).

Now, you're probably thinking, "But that makes trash hard!" That wouldn't actually be so bad, in my opinion. How many people's healers ask them to pull more? Wouldn't it be more fun it you had to pay at least a bit more attention to trash? Sure, that translates to longer runs, but fun is usually derived from challenges.

Holy Shield poses an interesting problem. It could be made into a blocking CD, increasing value or chance, but that goes too close to warrior mechanics, IMO. It could also be made passive, so that blocks would damage an enemy, but warriors already have a mechanic like that, Damage Shield. I guess it'd be up in the air. Maybe just for fun, for 20 seconds, attacks against you have a chance to knock the target back and deal X holy damage? Gives you some breathing room, but keeps aggro. One and a half minute CD. Or make it passive, so that melee attacks have a chance to cause your next ShoR to cause double damage. Something, anything, to make tanking more reactive.

Just my two cents. Thought I'd contribute.

I would like to add another thought into matters..

I don't think avoidance is the only problem, we had similar levels of avoidance in BC at times.

I think the problem lies with how health has changed from BC to WotLK too. Tanks are running with a hell of a lot more hp this time around, i'd estimate at 2.5x what they had in bc in equivalent gear, whereas BV hasn't changed in the same scale. Couple this with high avoidance values early on and you have block being the redhead stepchild when held up against parry and dodge.

I think one of the most damning things for Block, is that, armour is still a better mitigation stat than extra block value. As a paladin both count to wards EH due to being blockcapped, but armour still wins because it's a percentage reduction.
I cannot see a future for BR and BV staying as two stats in their current form.

I agree 100% that the Block Value stat needs to be phased out completely. The only purpose it serves at the moment is to add confusion to the system for newer tanks. Blizzard can find an elegant solution that would eliminate block value as a stat but still allow shield attacks to function in much the same fashion as they do now. Here is how I would do it.

1. Eliminate Block Value

2. Tie Shield based attacks to Strength

3. Change Blocking to a percentage based mitigation. For the sake of simplicity I'd say something like 20% to 25%, working against both physical and magical damage.

4. Block Rating would become the only Block stat. It would function just like Dodge or Parry. XX Rating = 1% chance to Block.

5. You would have to change Holy Shield, block would be too powerful to allow being "Block Capped" any longer. This isn't an issue because Blizzard has already mentioned that this is the plan. I'm not exactly sure what would make a good replacement for the current effect. Perhaps increasing the percentage blocked by an additional 5% for the duration, or adding a smaller percentage to the chance to block, 10% to 15%. Maybe even a whole new effect unrelated to Blocking?

If changes like these are made then Block once again becomes a worthwhile stat, some of the confusion is cleared up, and a stat is eliminated from the threat calculation for Warriors and Paladins which simplifies things.

Simple solution:

1. Retain BV from STR in some minimal form, and from the shield's rating.
2. Remove BV from gear.
3. Allow block to reduce an incoming hit's physical damage by x% + Block Value.
*Note - x% is not a big number and is less than DK cool downs.

Problems this solves:
1. Block does not scale with the encounter where CDs and Armor do.

Things this maintains:
1. Block is still useful, reducing overall damage taken but not as significant in intervals where DK and Druid CDs do.
2. Block remains an important stat for aoe tanking due to some small remaining block value.

Problems Created:
1. Warrior's Critical block and Shield Block are now defunct
2. Possible Paladin problems with Shield Block Rating

Possible Solutions:
1. Allow Critical blocks to scale x% such as by an amount such as 50% or 100%. Change shield block to where "All incoming blocked attacks are critically blocked" to prevent stacking.
1a. Alternatively, change Shield Block to allow Block to apply to spell. For the duration of Shield Block's CD, Spell Reflect is unusable and this mitigation cannot be affected by critical blocking mechanics.
2. Remove Block Rating from non-tier gear and increase the effectiveness of Holy Shield.

Another Solution
1. Add additional effect to Block Rating - Block Rating now increases your armor from Shield by x% for a blocked attack. Conversion rate to be determined.
2. Retain BV from STR in some manner.

What this solves:
1. Block now scales with gear through armor
2. BV remains useful for AoE encounters, but is mostly a flavor distinction.

There, block rating turns into something like Defense Rating in having two effects. It increases your chance to block, and armor reduction for blocked attacks. You could reword this "Your shield absorbs x% of an attack's blow" where x% is merely the derived percentage of armor gain from the shield. That is, if your shield gained 1000 armor on blocked attacks you'd absorb x% more damage, or you could simply have it absorb x% instead of involving armor directly (but in equal capacity). Then you simply scale the warrior's abilities with the new mechanic, and BV remains a nice flavor.