Last time I checked Mayo was having an awful season. That being said HELL F'ING YES would I take Mayo for JR. I was never a JR fan though he almost convinced me he had turned the page on his bad habits (driving more, less bad shots, playing a team game) last season but I suspected that once he got that long term deal he would revert back to what I now call "17 Three's LOL" mode aka playing like the low IQ player he has been for 95% of his career. It's a real shame because raw talent wise he could be a top SG.
So yeah, Mayo for JR would be a dream no matter how badly Mayo is playing.