Hockey players, particularly those on the forward line, are in action only for short periods -- usually 40- to 50-second stretches. Substitutions are allowed freely -- at any time play stops and often even as play continues. Because hockey alone among major team sports allows substitutions on the fly, smooth line changes are vital. And because of the importance of match-ups, line-change strategy is crucial.
Teams at various levels have differing limits on the number of players allowed to be active for a game. In the National Hockey League, for example, teams typically employ squads of four attacking lines -- a center and two wings -- and three pairs of defensemen along with two goalkeepers, a total of 20 eligible players. Of the four attacking lines, most teams use one "checking" line, a threesome whose task is to thwart the opponent's best scoring line.
When play is stopped, the team designated as the visiting team is required to promptly put a lineup on the ice ready for play. At that point, the home team may make its substitutions. The referee can decide that there have been unnecessary substitution delays and require an end to line changes. Although this seems to favor the home team, in fact, the visiting team can force the strategy by getting its best scoring line on the ice often. If the home team always counters with its checking line, then its own best scoring line receives more limited action.
Changes on the Fly
Line mismatches occur most frequently when changes are made on the fly. The best time to change on the fly is when the puck is deep in your own offensive end. If the puck is turned over in the neutral zone -- and certainly in your defensive end -- during a line change, it's likely to produce a goal-scoring opportunity for your opponent. Avoiding such situations also is why it's rare for all five players to be changed at once. Typically, the line change begins with the wing nearest the bench and continues across the line.
Line Change Mechanics
Substitute players cannot hit the ice until the players they are replacing get within 5 feet of the bench area. Preferably, the player leaving the ice enters the bench area at the gate farthest from where the puck is on the ice, and the player entering the game steps through the gate or jumps over the wall at the end of the bench nearest the puck. That procedure minimizes the time defensemen are off the rush or forwards are out of checking position.
If a player leaves the bench too soon -- before the player he is replacing gets within 5 feet of the bench -- the team shall be assessed a 2-minute minor penalty for too many players on the ice. The penalty also shall be called if either the player entering the game or the player leaving the game plays the puck with her stick, hands or skates, or if a player involved in a substitution checks an opponent. If a player involved in a substitution is hit by the puck inadvertently, there's no penalty. Players must leave the ice at their teams' bench areas or a 2-minute illegal substitution is called. A substitute is considered in play when both skates hit the ice. If a substitute touches the puck or another player before he is legally in the game, a 2-minute interference penalty is called.