I suppose if you hit free agency around the same time you could be posted, then free agency is more lucrative. There's no posting fee. I don't know whether a rookie contract is better than what could be made in NPB. Figure $5-10 million bonus if he's a top half draftee, then 3 years of MLB minimum, plus 3 or 4 years of arb. It's a heck of a bet on himself. There's probably others, but the one who comes to mind was Junichi Tazawa, who went from the industrial leagues (outside the NPB posting system) to the Red Sox organization. He pitched a number of years as a reliever. Signed December 2008 at 22, had a cup of coffee the next season in 2009, then stuck in the majors from 2011-2018 He made close to $24 million.