I would rank the middle guys as follows:
Ben Simmons - 3x All-Star, 1x 3rd Team All-NBA, 2x All Defense, 19 playoff wins (4 seasons)
John Wall - 5x All-Star, 1x 3rd Team All-NBA, 1x All-Defense, 20 playoff wins (10 seasons)
KAT - 3x All-star, 1x 3rd Team All-NBA, 2 playoff wins (7 seasons)
Elton Brand - 2x All-Star, 1x 2nd Team All-NBA, 20 playoff wins (17 seasons)
Wiggins - 1x All-Star, 3 playoff wins (8 seasons) - but trending positively
Ben Simmons, while a bitch recently, is younger and already more accomplished than KAT. He has legit DPoY potential and may be a key piece on a title team soon. Also people forget how good John Wall was a few years ago. He literally has 10x the playoff wins vs. KAT as the best player on the team.
As Bill Simmons mentioned, KAT has extremely low basketball IQ. He fouls and turns the ball over at the worst possible times, leading to losses. Here are his cumulative stats in the play-in game + playoffs this year: 19 fouls, 16 turnovers, -23 +/-
He is constantly in foul trouble FOR NO REASON. He goes after stupid offensive boards against the best transition team in the NBA (often leading to bonehead fouls).