SGA lead the league (amongst qualifying players) last season in +/-
Here are the +/- per 100 for last years All-NBA Teams.
Giannis - +7.0
Shai - +16.6
Jokic - +10.9
Mitchell - +11.0
Tatum - +9.9
Brunson - +3.1
Curry - +6.2
Ant - +4.9
Lebron - -1.1
Mobley - +11.8
Cade - +3.4
Hali - +4.3
Harden - +6.0
KAT - +7.2
J-Will - +9.6
Seems like there is a pretty strong correlation there.
Obviously the counter to this is that the top players play on the best teams and the best teams have the best +/-, but you can look at the +/- of the best teams (here are the top 4 from last regular season) easily see the story it tells at the bottom of their rankings (starting with the worst on each team):
Worst +/- per 100 on OKC: Malevy Leons, Alex Ducas, Adam Flagler, Ousmane Dieng, Dillon Jones, Branden Carlson... all of their bums
Worst +/- per 100 on CLE: Emoni Bates, Tristan Thompson, Javonte Green, Chuma Okeke, Craight Porter Jr, Luke Travers, Jaylton Tyson... all of their bums
Worst +/- per 100 on BOS: Miles Norris, JD Davison, Torrey Craig, Xavier Tillman, Jordan Walsh... all of their bums.
Worst +/- per 100 on HOU: Jack McVeigh, N'Faly Dante, David Roddy, Nate Williams, Jeff Green, Reed Sheppard, Jock Landale, Cam Whitmore... pretty much all of the guys they got rid of and a rookie.
Again, seems like a stronger correlation than you give credit for.
Here are the Spurs worst +/- per 100 guys: Charles Bassey, Bismack Biyombo, Devin Vassell, Keldon Johnson, Steph Castle, Malaki Branham, Jeremy Sochan. Draw your own conclusions.