Tried using the machine learning option for my dk. When doing bis it drops all my mastery. For you non dk ers mastery is life! After running a sim using my bis machine learning it comes out 588k. Now add my custom weights and you get completely different bis list with tons of mastery! it sims out at 608k. Not sure the machine learning weights are working right in the unholy dk world. I know there are only like 5 of us left but we need love too!
Can you link the gearing strategy that you made? Maybe something happened with that particular run.
http://www.askmrrobot.com/wow/simulator/report/369be1aee0c545629835b9f256a78866?weights=true&strategyId=fd6678ee1e424cfca67500d49bcc3f3c
this is the stat weights i used i got them from simulationcraft
My guess is that there are some setting which are different, causing the confusion.
If I use the default Ursoc weights (with machine learning turned on) to make a heroic level nighthold BiS set, I get this simulation results on Ursoc:
http://www.askmrrobot.com/wow/simulator/report/48d7e27b24b448e1bfa5607c98899c99
If I use your stat weights with all the same settings I get this result:
http://www.askmrrobot.com/wow/simulator/report/cdc9e47e032d4c25bdd0489a031fa25e
My guess is that you might be using different talents than were used for the default stat weights. The best thing to do is run a custom gearing strategy for your character, and choose machine learning.
The interesting thing to see here is that a high crit set can do just as much damage as a high mastery set.
The one you linked has the castigator talent choosen, that will bump up crits value a lot vs clawing shadows for mastery.
Would suggest you run a custom one as Swol mentioned. This is one i ran for my dk a while back using clawing shadows, can see it favors mastery much more.