I tried two pickup games.
In one game, I used the "inside box and one" tactic, and the best defensive player (best OD, best ID, best SB) in the lineup were set to defend as PG.
In the other game, I used the "outside box and one" tactic, and the best defensive player (best OD, best ID, best SB) in the lineup were set to defend as C.
For the inside box and one game, I cannot be completely sure, but for the outside box and one game, it seems like the best defensive player is probably the "+1" player.
Therefore, it is highly likely that my interpretation of those two games before is wrong.
My previous assumptions naturally do not hold.