Some thoughts.
On Tanaka:
This might be very true. Remember, he has 3 years before free agency. If the posting rules are changed enough, the team may think that they are better off not posting him this year and waiting one or two years. Remember, they just won the Japan Series, so posting him might make sense only if the team will get a considerable amount of cash.
There is only one that I know of is fairly accomplished at a very young age. Are teams already making a run for him?