Originally Posted by
Mugajak
Just drop the relevant/not relevant/rudeness "discussion". There isn't any way it's going to become productive.
Primordius' debuff does provide "real" haste to my knowledge, and you're just seeing bad luck. I had one spectacular LFR with over 85% uptime on ToB. Likelihood? Extremely low. Both haste and mastery builds are subject to RNG so long as you're using current-tier trinkets, that just won't change. For more information on the topic, see posts in the 5.2 trinkets discussion thread and Assassination: the nitty gritty thread.
For pulls with a haste build, when you get low procrate, your damage will not be as high as with average luck. For pulls with a mastery build, when you get a low procrate, your damage will not be as high as with average luck. The only difference is the luck floor - if you're expecting 5 procs on average and get 2, it sucks. If you're expecting around 8 procs and get 2, it REALLY sucks. Getting 2 procs with THAT much haste, however, is extraordinarily rare. Math for damage is all about averages, and across all pulls, there are points where reforging a mix of haste and mastery is over a pure mastery build. To my knowledge, there is no set for which full haste is ahead.
...and yes, ShC will recommend mastery > haste. The threshold for haste v. mastery at which this occurs varies with gear, but it does happen. Stat weights change.