BiL - it was always a best guess by the media and never directly attributed to Rizzo or the med / training staff. I think maybe McCatty or Davey used it or didn't deny, but it was either in response to questions using the number or they would cite a media report. I think the team has mentioned the JZ example to say they will shut a guy down when he hits his limit, but I don't think the number ever was etched on a tablet from Sinai. We don't know if the 161.1 for JZ was due to physical stress / fatigue measurements or was set regardless of how well his physique was handling the load.
I think the 160 became just something to make the argument more fun for BB tonight, MLB tonight, Fox / Yardbarker, etc... They wanted to make it clear and wooden. Now they treat this a big change. It isn't.