the opponents became much more difficult. Is it possible just his shooting percentage went down once he became the backup point guard? Yeah that's certainly plausible.

I think it was a fair coaching move to try to let JR be backup point guard to solve some of the minutes conundrum for too many wings and to let him showcase a more diverse set of skills, but from what I saw he wasn't particularly good at running the point guard. He had too much trouble with his own dribbling and with his passing.