Just look back the last couple of years. I think about three players last year were found positive in the Seattle system.
Jr might be clean, but then again, he might not. Right now we don't know, and I find it very interesting all the players who backed out of playing in the WBC. Are they all trying to hide something. I doubt it, but I suspect there are more players hiding from the WBC because of independent testing than there are because of "injury concerns" or "I just need to work with the team right now".