I have some question about the haste cap of ret/prot paladins. Several guides, both for ret and prot, mention 17000 haste as the haste softcap, but don't really tell why. I also read somewhere (can't find it any more) that 21000 is the hardcap.

So lets do a bit of theory:

- 17000 haste equals 40% haste.
- Take the 10% melee haste raidbuff and we have 50% haste.
- 50% haste reduces the GCD from 1.5s to 1.0s. It cannot be reduced any further even with more haste.
- 50% haste means our Sanctity of Battle reduces the cooldowns of our main abilities also by 50%.

Conclusion:

Having more that 50% haste would be useless to us, since even if our abilities had a lower CD, the GCD wouldn't allow us to use them more often, so the only effect increased is melee attack speed, making haste less useful than mastery or crit after this point.

But while this sounds logical, it isn't how it works.

- Even if Sanctity of Battle explicitly says "Melee haste effects" and the 10% haste raidbuff reads "melee and ranged attack speed", having the raidbuff doesn't have any influence on our ability cooldowns.
- Having 40% haste and the 10% raidbuff will not give us 50% haste, but 54% haste. (I have no idea why, it should be either 50% or 44%, but the ingame tooltip says 54%)
- I have no idea if the 10% melee haste raidbuff lowers the GCD or not.

So, what is the explanation for a softcap at 17000 haste?

Is the cap at 15455? (36,4%+melee haste raidbuff = 50%)

Is the cap at 18113? (42,6%+spell haste raidbuff = 50%)

Is the cap at 21250? (50% without raidbuff) = possible hardcap?