Thing is, I love me some IT. But, the defensive argument, the playoffs argument, they are both real.
Kyrie has played almost 2000 playoff minutes with a DBPM of -0.2. In ~13000 regular season minutes, it is -1.5.
IT checks in at -2.7 (regular season/ ~13000 minutes) and -1.5 (playoffs/ 860 minutes).
Kyrie is a bad defender, yes, but IT is measurably and significantly worse, and the difference is larger in the playoffs.
How about we just continue thinking IT is amazing, and also be excited about Kyrie being a potential upgrade. Crazy idea, I know.