Yeah, I've got a couple sites I use for those stats, one is NBA.com, I won't bother to post the link because when you're digging that deep into stats the URL is massive, but their stat tool is easy to use.
The other is 82games.com. Very detailed, very heavy on rotation based stats, also, it is unfortunately not updated very often during the season, like probably 3 or 4 updates all year.
Phoenix Suns, NBA player and team stats including plus/minus data and best five man units
www.82games.com
There is the Suns on court/off court and rotation data for the season Payton was here. If you click through the rotation players you'll find that while Payton doesn't have the lowest overall +,- stat, his numbers per minute/possession blow anyone else out of the water.
But yes, we certainly tanked, I don't believe Payton getting shut down the last couple weeks had anything to do with us not wanting to win, but was more about giving other guys a look... because Payton was clearly hot garbage, as the stats back up.
I was debating the claim that last year was Payton's worst season, I said it was bad, but he run here was much worse and, statistically, it is hard to challenge that. This year his win shares per 48 stat was a putrid .032 (league average is .100), his rate in his 19 games here was a "is my grandma playing?" level of bad at .009.
I really want to say that I am only continuing this conversation about how terrible Payton is because I keep getting directly challenged, I don't want to beat a dead horse. I think we would all agree that if our season at any point hinges on the skills of Elfrid Payton then something has already gone horrendously wrong.