There is a tactic called ‘matching bowls’. As first explained to me, matching bowls means intentionally placing your bowl close to a bowl or group of bowls belonging to the opposition because these could all count against you should the jack be displaced. In fact, this is not an adequate explanation of the tactic. I pieced together a better understanding by watching the Indoor World Championships on Youtube.
Matching bowls may be useful towards the end of a match when
your side is well in the lead. The purpose of the tactic is to limit the
opponents’ possible scores in the remaining ends. The normal concern is that
the opponents might trail the jack with one of their last bowls to a group of
catcher bowls and thereby achieve a big score. Matching bowls correctly requires
you to place a bowl between two of
the opposition bowls. If your bowl ends up sitting exactly on a line between
the centers of two opposing bowls, it
can be proven geometrically that there will be nowhere on the rink that the
jack can end up where both of the two opposing bowls can count.
This understanding should be combined with an awareness of
where the jack can realistically be trailed to decide upon the best placement
of the matching bowl.
