Sponichi posted an interview with Chihiro Kaneko on January 16 that covered more on his thoughts about the Majors. Here is one of the more interesting sections.
You exercised your domestic FA option. You struggled with the idea of going to the Majors through the posting system.
I was a difficult decision. We won eighty games, more than Softbank, but we lost in winning percentage. It was worse than just finishing in second. I wanted to win with our current team. But I was also worried that this year might be my last chance to go to the Majors.
You could have earned your international FA option if you waited one more year.
Yeah, but in my case, I would have to log quite a bit of time this year to get it. Getting hurt would mean another year. The posting system changed and I thought this was my chance to talk to all kinds of teams. I thought this was a really good thing for players, being able to exercise the domestic FA option and get posted, we could talk to every team. I thought this year was my best bet.
You didn't have much time to think since you had the NPB-MLB series in November.
The NPB-MLB series was big so there wasn't able to really think about my FA option. I'm not good at doing two things at once and I didn't want to decide without thinking things through properly, so I exercised the option.
You gave up on posting after the NPB-MLB series.
Things might have been different if it was something I wanted before I turned pro. But the team hasn't won a championship since I joined and I started to think that I might have another shot at the Majors.
At around the same time, you had problems with the elbow.
The elbow was something separate. It surfaced after I decided to play in Japan. There might be people that think I gave up on the Majors because of it, but that isn't what happened. That's really the way it played out.
Source: Sponichi 1/16/2015