Short-handed situations (5v6, 4v5, etc.) call for zone defense. Instead of boxing out, Ds front the two opposing forwards near the net. This allows them to get in the way of point shots and help F3 protect the slot. In the example above, fronting turns a 5v6 into essentially a 5v4, which is great as long as the puck doesn’t get to the attackers at the top of the crease.