User blog comment:Kaido King of the Beasts/Chapter 818: Stepping Stones to One Piece/@comment-25319479-20160304002313/@comment-10543621-20160304015000

I think Roger spilled everyting to WB before he died. From what was hinted, WB could very well have made his way to Raftel and became the pirate king if he wanted to, but simply didn't because he valued his 'family' more than being pirate king.