About Kanter:
He's not better than TT. His RPM is -2.72 because his defense is -3.87, the WORST IN THE NBA for centers. Only 7 centers in the NBA have a DRPM below -.70. Even Barnani and Matt Bonner are ahead of him. He's so terrible defensively that teams he's on don't outscore opponents no matter how many points or rebounds he gets.You might think: "Well, with Serge Ibaka in there, he'll be OK." Nope. In 238 possessions played with Ibaka, OKC gave up a DRTG of 111.5 with Kanter/Ibaka on court. A 111.5 DRTG would put you at 29th out of 30th teams in the league. Even with a great perimeter defender in Roberson who doesn't do anything else, the DRTG is still 110.
Utah ORTG with Kanter ON: 107.8
Utah ORTG with Kanter OFF: 104.2
Utah DRTG with Kanter ON: 111.2
Utah DRTG with Kanter OFF: 102.2
Utah was 9 points per 100 possessions worse defensively with Kanter on court. In total, they were 5.4 points per 100 worse with Kanter on court.
OKC ORTG with Kanter ON: 112.8
OKC ORTG with Kanter OFF: 106.2
OKC DRTG with Kanter ON: 111.7
OKC DRTG with Kanter OFF: 103.9
OKC was 7.8 points per 100 possessions worse defensively with Kanter on court. In total, they were 1.2 points per 100 worse with Kanter on court.
In the modern NBA, your center has to protect the rim and play against pick and roll.
He's 80th out of 83 in FG% allowed at the rim among those who faced at least 5 shots at the rim per game.
He's 104th out of 105 players in post defense among those who played at least 70 possessions.
He handled the roll man decently (top 30% overall).
I wouldn't want him as a starter on my team.
In addition, centers have the highest average impact on defense due to defensive rebounding (they get the most and end possessions) and because of their rim protection via help defense.
Out of 73 centers, only 20 had negative defensive impacts and only 7 had a DRPM below -.70. A team EXPECTS the center to be a defensive strength. Kanter's negative defensive impact is severely below even the average center's.
Meanwhile, 70 out of 99 SGs had negative DRPMs. A plus defender at SG is a great plus (thank you, Iman) but one expects a negative DRPM here. A guy like Crawford is awful at -4.3 but he's not as far below the average SG as Kanter is below average compared to other centers. 63 of 84 PGs also had negative DRPMs.
He's young and can improve but he's shown no signs thus far. In light of how awful Kanter is at defense compared to other centers who are supposed to have positive defensive impacts and considering the fact that the modern NBA requires a center to be strong defensively, one can make an empirical case that Kanter is one of the 5 worst defensive players in the league. Do you want that player as a starter?