But yeah, looking at those logs I can tell exactly what every single spike is (and it is all some predictable boss ability)
Just look at your own logs and check damage taken.
Haste build will never have a smoother damage in-take on a short burst spike than mastery. Unless it is 100% magic damage ofc, in which case, stamina would be better either way.
I am haste stacked not mastery stacked. Since the damage in-take is not a concern either way, can be handled with own cooldowns. DPS is the only issue for 10 man tanks really.
Though, if bosses did say 50-100% more damage than currently, then I would probably be mastery stacked since it is better for survival.