I think back to a clip posted on this website of Darvish throwing what looked like a long, sweeping cutter that started way outside and cut back what looked like 2 or 3 feet, ending up at the shoe laces of the guy trying to hit the ball. It was the definition of a wipe out pitch. That 5-10 second clip made me a believer. His stuff is nasty and if he stays healthy, he could become a top 10 pitcher.
I think his biggest problem last year was the enormous pressure ... which is totally understandable. What made him successful in the 2nd half was that he settlled down and figured out how to pitch to MLB hitters.
If he stops trying to strike everyone out and continues learning that the key is control and not so much the 95 mph fastball, we might see him in the Cy Young discussion. If the Rangers are contenders, which I'm not convinced they are, I could see him winning 20 plus games... but he has to cut down on the walks.

His 2 seamer was actually his better fastball. He did better when he pitched off of that and had his slider working, and saved his 95mph 4 seamer for when he wanted a little extra. I have no doubt he'll be a force this year and it wouldn't surprise me to see him finish in the top 4 of cy young voting.

@Romeo - Some of my favorite Yu moments were when he did just that with his 4-seamer; it looked like it was about 130 MPH.

No it did'nt.

It's fun to watch some of Yu's old videos from Japan. The radar gun reads shit like 140+ km/hour. Makes you think he's some superhuman guy.