As analytics continue to evolve, goaltending analytics continue to lag behind.
As possession metrics, zone starts and usage rates add context to NHL skaters, the most common way to assess a goaltender remains to be save percentage, a stat that was introduced to the NHL for the 1983-84 season. I have made attempts to move goaltending evaluation forward and Steve Valiquette’s introduction of the Royal Road has given even greater context to understand shot quality and its effect on save percentage. The concept of pre-shot movement highlighted in his research is beginning to offer some insight into the future of goaltender analytics.
The Royal Road is a line that goes directly through the middle of the ice from one net to the other. It separates the ice into two equal parts. A puck crossing this imaginary line immediately preceding a shot increases a shooters scoring opportunity by over 10 times. This is because goalies have limitations to their movements and while laterally tracking they are forced to open up.
While reviewing NHL footage, a pattern of success began to emerge. These high percentage opportunities were labeled Green goals because they do not allow the goaltender to gain half a second of clear sight prior to the release.
Green goals account for 76% of all goals reviewed. These shots are high percentage opportunities and fit into seven different criteria:
- Passes across the Royal Road – 22%
A pass across the Royal Road below the top of the face-off circles account for 22% of all goals. This pre-shot movement is essential to make life difficult for goaltenders because when the puck moves laterally with speed, it forces the goaltender to set their depth and angle while in transition.
- Screens – 10%
If a goaltender cannot view the puck it decreases his chances for success. When players effectively layer in front of the goaltender, their chance for success increases as the goaltenders visibility decreases.
- One-timers on the same side of the Royal Road – 9%
These are plays that generally originate from behind the net and are quick passing plays to a shooter in the slot on the same side of the royal road. It is tough for a goalie to pick up because he only has half a second of clear sight and set up time before the release from the shooter.
- Broken plays – 9%
Broken plays can cause havoc for goaltenders because they set for a situation that can be altered by a quick change in puck direction. Passes or shots that deflect off a skate/stick into the net. Puck direction that when altered act like a royal road pass as it forces a goaltender to move east/west while in recovery mode.
- Possession across the Royal Road – 8%
If a player enters the offensive zone with speed, a defense happily exposes the exterior and attempts to clog the middle. They do this with good reason. They are attempting to deny the attacking forward the ability to cross the royal road. A shot from above the face-off circles and no lateral movement will results in around a 3% chance to score. If the attacking forward is able to cross the royal road through the slot, his chances increase to 33%.
- Deflections – 8%
Deflections are extremely challenging because they initially present themselves as a red shot. A goaltender sets for the initial path and plane but when they are altered, the maximum coverage becomes compromised. The closer the deflection to the net, the lower chance for goaltender success.
- Green rebounds – 8%
A green rebound is any scoring opportunity that comes off a goaltender that originated from the green shots listed above. These high end opportunities are difficult to control for goaltenders because pre-shot movement or lack of visual attachment, makes it difficult for goaltenders to have proper hand position to deflect pucks into safety areas, as well as set for shots so they can corral them into their chest for a stoppage in play.
Green opportunities account for over three quarters of all goals scored in this study, yet they only account for one quarter of all shots taken during a typical NHL game. To put that in perspective, during an average 30 shot NHL game a team will take 22-23 Red shots.
Red Shots are low percentage shots on net where Goaltender has more than a half a second to see the shot.
Goaltenders have an extremely high success rate with these opportunities because without lateral movement across the Royal Road or significant pre-shot movement, they are able to set angle, depth and create strong visual attachment to the puck. At this point the shooter is relying on either a perfect shot or goaltender incompetence for success. Only 18% of goals were scored in this situation.
Red Rebounds are possible entirely because of goaltender failure. They differ from green rebounds because of the nature of the initial shot. When a goaltender fails to control an easier opportunity he creates a red rebound.
All rebound opportunities have a higher probability of success. Rebounds of controllable shots are self-inflicted by the goaltender, so as a shooter it isn’t the best plan to rely on this incompetence.
A yellow shot is defined by an area created by starting from the center of the net and creating a line towards where the boards and center line connect. At the intersection of where this and the vertical Royal Road intersect, we connect them to form a triangle.
A yellow shot is defined by any red shot that takes place inside this triangle. These shots are extremely rare because an NHL defense is specifically designed to take these opportunities away. It isn’t easy to skate into this area without being forced to cut laterally or wide and because of this, they only occur once or twice every 2-3 games.
The yellow shot is preferred to a red shot because of the proximity to the scoring zone in the slot area. As a result, it has a 300% greater success rate than the red shot, but without the benefit of deceiving the goaltender with pre-shot movement or reducing a goaltenders visibility, the success rate is below the preferred green shot.
All of these factors need to be considered when viewing a goaltenders workload because they have a direct impact on their save percentage. Goaltenders playing behind elite defensive players or a system, are consistently exposed to more red shots and have limited exposure to the more dangerous green shot.
When we accept that over three quarters of all goals scored in the NHL are of the green variety, we can begin to move goaltending analytics into the new millennium and push toward the creation of a goaltender independent statistic.