For personal damage, after the increase in value of mastery to 2.3% for each point
1700 mastery rating =9.497 mastery points
9.497 mastery points x 2.3% = 21.843% damage increase
So for a trinket to beat mwc
It has to be greater than the 21.843% damage increase with meta for 36 seconds every 2 minutes
With the 21.843% damage increase for 20 seconds to your pet every 2 minutes.
In addition to the 21.843% damage increase to your doomguard once or twice a fight.
The static bonus has to be better.(Which should be the case)
I think this would be interesting (assuming any damage triggers it)
http://ptr.wowhead.com/item=77990
42.119% damage increase