I have no idea where the information is coming from. I'm only reporting what Jon Heyman is reporting.
Beat reporters like Heyman and/or Rosenthal never ever reveal their sources. If they did, they would never receive inside information from teams, players, or their agents ever again. Bill Madden use to get his inside info from George himself. Michael Kay would get his inside info from Billy Martin back in the day. Both would never reveal them because if they did, their gravy train of inside information would come to a screeching halt.
