Most goals against start at the bench door

The line change is the only moment in hockey when a team voluntarily plays a man short, and it is barely coached.

Ten seconds. That is the whole window, and it is where a startling share of goals are born.

A change on the fly is a controlled numbers disadvantage. For a stretch of a few seconds the team changing has one skater climbing over the boards, one skater arriving at the boards, and a puck somewhere in between belonging to nobody. If the other side reads it, they have a four-on-three through the neutral zone against players who are looking sideways at their own bench.

Good teams treat this as a set piece. They have rules about it: nobody changes below the top of the circles in their own end, the puck-carrier is the last man to go, defencemen change on possession only, forwards change on a dump-in that is retrievable. Those rules exist because somebody sat down and worked out where the disasters come from. Bad teams have a vague instruction to keep shifts short and then wonder why they concede off the rush against nobody in particular.

The tell is easy to spot from any seat in the building. Watch who changes when the puck is on your own defensive wall and a battle is still unresolved. If two forwards leave that battle while it is live, the coach has not sold the rule, and the third forward is about to be outnumbered.

Fatigue makes it worse in a way that is slightly counterintuitive. A tired player changes late, which lengthens the window. He also changes at the worst moment, because the decision to go is made by legs rather than by the situation. So a team that is being outplayed changes badly, gets scored on during a change, and the goal is filed under a defensive breakdown when it was really a shift-length problem three minutes earlier.

I would put a coach on the bench whose only job is the door. Not a joke. In a league where a full-time analyst tracks entries, someone should own the single most predictable disadvantage a team creates for itself, and should be allowed to shout at a winger who leaves early because he wants the next offensive-zone draw.

The puck does not care that you were tired. It only notices that for four seconds there were four of you.