The fact that your bigs (i.e. the players set to defend at PF and C) end up defending some outside shots is a consequence of defensive rotations and stuff
But, it's not on early "transition" shots. There shouldn't be any defensive rotations once the zone is set. I wonder how the engine finds the weak point of D to exploit in zone. How does my opponent's SG ends up shooting over my PF defending as C, but not over SF d. as PF?