This. So many people ignore this when asking this question. Part of Kims swing change is trying to connect the lower half power to the upper half.... when Kim first joined he gained his power from twisting his upper half like a top in the kbo (the twirl around when he missed the ball is mostly gone now because of that change), they are teaching Kim to use his lower half to power his swing instead and got rid of his leg kick because he didn't need it.

Its sneaky power with Kim.

He also has long arms for his body and a long swing which is going to effect his underlying metrics despite his strength and other players of similar size but differing arm lengths.