the only way to refresh enrage in cs is br, since using bt in cs is stupid and a waste of dps
I'm sorry to be the one to point out that this isn't the case. You may also not be aware that the rotation is using BT during CS (as it should be) - go see for yourself on a dummy.
For reference:
Fury Warrior DPS Rotation, Cooldowns, and Abilities (MoP 5.4) - Icy Veins - skip to 6.3.2. During Colossus Smash.
One point that is outdated in the guide is the stipulation that SB must always be the first GCD within the CS period. This is no longer as crucial with the new 3/4 and 4/4 upgrades to the Eye of Galakras. The cooldown for SB moves below 20 seconds, meaning it can "catch back up" if delayed.
and using br when enrage is not up is something the cr already does
The point I am trying to make is that if you are able to refresh your enrage during the CS (either BR or BT is coming off CD) AND still get your SB off during the CS window it would be better to delay it until you are enraged. The benefit from being enraged is the same or greater then the increase from being within the CS window - so it is well worth aiming to be enraged for your strongest attack during the CS window (SB) if it is possible to do so. If it isn't possible (BR wont be off CD and no further BT opportunities) then it should cast anyway at that point. Another point to note is when delaying it should avoid leaving SB until the final GCD of the CS window as SB has a travel time and can reach the target after CS has expired on some bosses.
This would mean you would essentially want to delay SB if not enraged + having at least 1 stack of RB during CS if:
- BR will be off CD by the 3rd GCD of the CS period
- BT will be available by the 2nd GCD of the CS period (You could leave it until the 3rd GCD if you wanted to ignore the travel time issue on SB)
If neither of these conditions are met or the BT is available and does not crit, it should cast anyway. There is also no point delaying if you have 0 stacks of RB available as the loss from using a filler during CS will not offset the gain from delaying SB for enrage.
One point I do agree with is that as gear increases this situation becomes less and less likely and therefore less relevant.