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How are they scoring goals?
Updated: Tuesday October 30, 2001 7:55 PM
By Marc Foster and Chris Apple, special to CNNSI.com One of the problems with inventing a new science is that a lot of time is spent elevating the understanding of those being instructed. This week's column is not meant to intentionally come off sounding like a lecture, but in a way it is. A couple of weeks ago we introduced Bill James' Pythagorean equation and applied it to hockey. However, its uses are not limited to final regular season GF and GA for entire teams. Goals can be broken down into even strength and special teams. Then the equation can be applied again. The equation can also be applied to individual skaters, but that's another column. Let¹s start first with defining our terms:
PPC = Power Play Chances
PP% = Adjusted Powerplay percentage = (PPG-SHA)/PPC I have never liked traditional PP percentage and PK percentage. The above versions account for shorthanded goals. A shorthanded goal is a credit to a penalty-killing unit, while allowing a shorthanded goal counts against the power play unit.
ES Weight = Percent total GF and GA that were Even Strength = (ESF+ESA)/(GF+GA) Ideally, there would be exact figures for team ice time in even strength and special teams situations to derive the above weights. Instead, weights are established based on relative impact. Thanks to James Karkoski, detailed special teams data back to the 1963-64 season has been recorded. Based on that data, it averages out to about 72 percent even strength and 28 percent special teams. In a 60 minute game, that works out to be 16.83 minutes a game where one team or the other is shorthanded. That’s not an unrealistic figure and will have to do until better data is available. Not all teams have the same weights, however, and those ranged from an ES Weight of 57.95 percent for the 1987-88 Penguins to 82.97 percent for the 1976-77 Canadiens. STPyth Percent = Special Teams Pythagorean Winning Percent The above is same as the traditional Pyth%, only substituting PPG-SHA for GF and PKG-SHF for GA.
ESF = Even Strength Goals For Again, same as Pyth%, substituting even strength GF and GA.
ES GP = Total Games Played at Even Strength = ES Weight * GP Ever wonder the true value of even strength goals for and against in terms of actual wins and losses? Well, just take the ESPyth% and multiply it times ES GP as derived from ES Weight, and wins and losses can be determined based on a team’s even strength play. The same can be done with special teams using the equations below.
ST GP = Total Games played with Special Teams (ST Weight * GP) In the grand scheme of things, it would be nice if these W-L records could be completely adapted for hockey, but in reality they can't. Any inclusion of ties or regulation ties would be arbitrary. So, what does all this algebraic nonsense give us? First off, it tells us exactly where teams may be winning or losing their games.
There are a few interesting things first off, Detroit was 14.3 games over .500 on special teams, yet only 6.5 games over on even strength. It’s no secret where their wins came from. On the other hand, New Jersey thrived in even strength situations. Then there are teams who are strong in one area, yet weak in another. Toronto and Pittsburgh were over .500 on even strength, yet below it for special teams. Carolina, Nashville and Montreal were the opposite, both above .500 on special teams, but below on even strength. Here's a look at some selected historical seasons.
The first two are easily the worst even strength seasons out there. Fortunately for the Isles, they’re special teams play was almost respectable, with a .417 STPyth%. The Caps were not so lucky in their first year, but we’ll get to that in a moment. The Canadiens dynasty of the 70's were easily the best even strength teams on record. The top two are shown, but in reality the next two, 1972-73 and 1975-76, don¹t look any different statistically from 1977-78. Nine of the top ten seasons coincide with the existence of the WHA, and I wonder if team depth played a role here. Say what you will about the recent expansion, but counting the WHA there were more teams and less parity in 1974-75 than exists today.
The expansion Isles scored only 28 power play goals while allowing 13 shorthanded for a net advantage of 15 goals. In a shorter 70 game season the 1964-65 Bruins had the same net 15 goals on 25 PPG and 10 SHA. The Detroit season listed points to the amazing talents of coach Scotty Bowman. These recent Detroit teams excel in special teams whereas his Canadiens teams of the 1970's weighed in and excelled in even strength. He’s winning with different methods in what have become different eras. Amazing. Marc Foster is a research analyst in Fort Worth, Texas. Chris Apple is a database analyst/Internet specialist in Lincoln, Neb. Together, they operate HockeyResearch.com, and hope to one day elevate statistical research in hockey to the level seen in other sports.
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