I have reported this bug (feature that is not fun, not logical and should not be) a LOT of times this expansion so far. Now I resort to a forum post because with the 7.3.# raid coming and the new Fury warrior set pieces this bug will be a plague to all fury warriors.
The bug comes in two forms, but in both cases it does the exact same via the same stupid, irrational behaviour of the spell Rampage.
Since the Legion prepatch hit in WoD this has been how it has worked and I have been reporting the bug ever since.
It has to do with how Rampage consumes buffs such as the one you get from critting an execute (offhand or mainhand) while having Massacre talented or the one you get from Whirlwind (making next Bloodthirst or Rampage cleave)
Critting either the offhand or mainhand Execute with Massacre talented yields a buff that grants a free use of Rampage.
Let's take the Massacre case to start with. Say we do an execute rotation with Massacre talented and it looks like this:
1) Rampage
2) Execute (crits yielding Massacre buff, free next Rampage)
3) Rampage
What do you expect to happen? We ofcourse expect the Rampage in 3) to be free. This has not strictly been the case at all since the Legion prepatch that reworked Fury in the end of WoD. It has to do with how much haste (and thus how short the GCD is of the warrior that undertakes this rotation).
Why have people not complained about this? It is painfully easy to miss. Not many people played fury in Emerald Nightmare (and haste levels were at their lowest since it was the beginning of the expansion) where Massacre was amazing. Many people played Fury in NH but Frothing Berserker was used instead. In ToS not so many people play Fury and if they do, they do not use Massacre.
My understanding is that it occurs somewhere between 40% and 60% haste that the Rampage in 1) checks and consumes buffs after global 2) has occurred, yielding situation where you pay 85 rage for a Rampage, then crit an Execute (which should reward you with a free Rampage, but then the Rampage that you paid 85 rage for already also consumes the free Rampage proc meaning you paid 85 rage + a free Rampage proc for 1 rampage which is absolutely CRAZY for fury whose sole objective is to stay enraged. It can completely stop you dead in your tracks to have this happen.
The second case is what you're going to hear people complain about in the coming raid tier. It has to do with the Meat Cleaver buff that Whirlwind grants (Meat Cleaver makes the next Rampage OR Bloodthirst cleave 50% of its damage to 4 other nearby targets).
Imagine you are cleaving to some adds from a boss:
1) Whirlwind (I get Meat Cleaver, I expect my next Rampage OR Bloodthirst to cleave)
2) Rampage (cleaves succesfully!)
3) Whirlwind ( I want to quickly make another Rampage OR Bloodthirst cleave )
4) Rampage (does not cleave because the Rampage in global 2) consumed the Meat Cleaver proc from 1) so late that 3) overwrote the Meat Cleaver from 1) before being consumed by the Rampage in 2)).
PLEASE. PLEASE. FIX THIS INTERACTION. It makes NO SENSE to have it SUDDENLY be an issue depending on what haste you have on your gear, whether you have Sephuz or War Machine or Bloodlust or other buffs that give haste active
It is a MASSIVE issue because Fury warriors CONSTANTLY jump between 30-39% (whatever gear you have currently) to upwards of 70-75% haste via War Machine or Bloodlust.
I can probably phrase this better if you need me to. I can also do more elaborate examples but hopefully the point comes across:
THE ISSUE IS: Rampage consumes buffs so late that sometimes (depending on your haste level which is very often high enough at this stage of the expansion) it consumes procs obtained AFTER said rampage was used completely screwing up your plan for the next globals and the difference is ABSOLUTELY MASSIVE.
EDIT: Currently the best Fury warrior cleave damage that you'll do in a mythic+ trash pack with War Machine, Sephuz or Bloodlust active and Odyn's Fury on cooldown, is to:
1) Whirlwind
2) Battle Cry + rampage, then
3) wait till Rampage consumes Meat Cleaver from 1)
4) Whirlwind (applying new Meat Cleaver)
5) Rampage again now that it'll actually cleave