This is one of those things I just don't get at all. I like Yu Darvish, I expect him to have a good year. I just think where he is being drafted in many leagues is insane. Paul Sporer who I admire greatly and who sells his own pitching handbook and I suggest you buy it, drafted him over Cole Hamels in a LABR draft recently. http://www.rtsports.com/LABR-Mixed-Draft
Lets take a real look at Darvish here.
I will start this off by saying it is just as likely that the league adjusts to him as he adjusts to the league so assuming there will be a giant step one way or the other is probably being overly optimistic or pessimistic. He gave up a wOBA of .293 or higher every month last year except September. Basically Sept saved him from being a big disappointment for most. His stats last year were 3.90/1.28, 16 W, 221 K.
Hamels gave up wOBA of .293 or higher 2 months. His stats were 3.05/1.12, 17 W, 216 K. So he beat Darvish in every single stat except K which was close while being more consistent and having a longer track record of success.
I got pumped up about the big Sept of Darvish too but lets not read too much into this. He is going at an insane draft position in most drafts. He is going over guys like Cain, Hamels, Wainright and Bumgarner who all have longer track records and were better than him last year. You never want to draft a guy where he HAS to break out to be worth his pick, that just isn't value. Even if Darvish breaks out most of those who are drafting him this early aren't gaining any value.