It's all the system and personel around him. Bigmen tend to get all the metrics love in good defensive teams because they are the ones that get the rebounds, the blocks and the "contests". If Amen Thompson gets all up in his guy's face and makes him get all dis bobulated to the rim, all Sengun has to do is just wait in his place with his hands up. Amen, Brooks, Eason, the Rockets are packed with great perimeter players, those are the real MVPs, tbh.
On another note, I don't see the Rockets as real contenders, tbh. They don't have a true franchise player and they have a bunch of players with glaring weaknesses that get hidden on the regular season but could be exploited on a playoffs series.