This has been bothering me since the start of WoD and I tried to think about it in diffrent ways, calculated it several times and simmed it, but it just does not change at all:
Multistrike is such a bad stat for tanking, you might as well have no stat instead of it
I keep thinking about what Blizzard said about removing reforging (We will make the stats closer in value so you don't have to reforge!) and removing all defensive stats (We will add defensive value to all offensive stats!) but it just does not work for multistrike and prot.
And then to top it off, you get thrown alot of it in your face, even on our set!
To get 4pc T17 you have to wear at least one of them, since 2 parts of the set have it.
I was hoping they would do something against it with 6.1 but so far nothing. Makes me really sad.
Simmed my toon yesterday and multistrike was worth 0,02 for damage taken, versatility was worth almost 100x with 1,99 and versatility already is our 3rd stat, Crit and Mastery being both better (though at least somewhat close with 2,3 and 2,1).
The only saving grace might be, it's strong for dps, but crit is better while being a really strong defensive stat
Note: Haste is in a similar boat, but not quite so massive in "badness".