I think that a defensive bot shouldn't automatically be a wall bot. With the relatively open field layout, trying to block off a portion of the field to prevent scoring does not seem quite as feasible, or at least as easy, as some other possible defensive solutions. It worked for Round Up
and Gateway, but it might not be quite as good for Sack Attack.
Defensively, you're trying to prevent them from scoring as much as your alliance can score. Physically blocking off the goals might work, but it just seems really hard. The other option is to make it impossible for them to access any sacks to score with, although there's quite a lot of them all over the field, so it would be pretty hard to do that too.
Actually, I'm not entirely sure that making a purely defensive bot is that viable this year. Defensive actions, yes, but maybe not a robot that is purely designed around preventing opponents from manipulating game objects and moving them to a scored area for their team
. Might as well work on the other half of the game (manipulating game objects into your own scoring zones).