#4. Timeline

Hockey fans often hold onto the past, referencing expansion, a decline in physicality, or anecdotal player exploits as signs of dilution in talent. In our preliminary introduction to PPS, we raised persuasive arguments that the quality of the NHL has greatly improved over time. The NHL’s available talent pool has grown exponentially since its creation, steadily adding world-class talent from the United States and Europe into its ranks. Advances in fitness, nutrition, training, coaching, and equipment, in concert with life-altering wealth available to modern players, continually raises the standard of play.

The NHL, established in 1917, entered what would soon be considered a golden era of athletics. Dominant performances were commonplace, larger-than-life athletes achieving remarkable heights well before the advent of television. In tennis, Bill Tilden won 98 consecutive matches across 1924 and 1925. In baseball, Babe Ruth’s 60 home runs in 1927 exceeded every team in the American League. In 1930, competing as an amateur on a part-time basis, while practicing law, Bobby Jones won all four major golf tournaments in a single calendar year. While these extraordinary feats represent the world’s best at the time, the gradual advancement in the quality of competition has made outliers of this nature extinct in the present day. As such, should Connor McDavid (circa 2021) dominate comparably to Howie Morenz (circa 1927), the performances cannot credibly be held in the same regard. As quality of play rises, the increment at which the best players should expect to outperform their peers inherently narrows.

One might question how good Leon Draisaitl would be in a six-team NHL. Well, for starters, he wouldn’t be in the NHL at all, given it was essentially a Canadian hockey league at the time. A basic review of league demographics invalidates any claim the Original Six was more exclusive than today’s NHL; the hockey-specific country data below is courtesy of the invaluable quanthockey.com.

NHL DEMOGRAPHICS, 1950-51 VS. 2019-20

 1950-512019-20% Change
# of Canadian-Born NHL Players153413+270%
% of Canadian-Born NHL Players94.4%42.6% 
# of NHL Players Born in All Other Countries9557+6,189%
% of NHL Players Born in All Other Countries5.6%57.4% 
Canadian Male Population, Aged 20-392,102,9985,235,622+249%
NHL Nationality Data from Quanthockey.com; Canadian Male Population data from Population of Canada 1950 - PopulationPyramid.net and Population of Canada 2020 - PopulationPyramid.net

The NHL of 1950-51 was a selective fraternity, only 162 players privileged to slip on a jersey. Yet, its exclusivity extended beyond its limited roster spots, a sport played almost entirely by Canadian-born athletes. Only nine players(!) were born outside Canada’s borders. Despite four of six franchises calling the United States home, only three players were American-born. The colour line had yet to be broken, Willie O’Ree’s trailblazing 1958 debut still years away. It was a six-team league of Caucasian Canadians, with few exceptions. Was it difficult to land and hold down an NHL job? Absolutely. But the NHL was decades from considering itself a global league.

Fast forward to the present day. The NHL has grown considerably, with 26 more franchises and larger rosters. In 1950-51, 19 out of every 20 players was Canadian-born, while the modern NHL features only eight or nine Canadian-born players per 20. Interestingly, the pool of males in Canada (using 20-39 year-olds in the population) has grown 249% in the last seventy years, while the NHL’s Canadian-born growth is at 270%. Expressed by odds, the NHL of 1950-51 included one Canadian-born player for every 13,745 pro-hockey aged men living in the country, while the NHL of 2019-20 included one for every 12,677. This is a simplified analysis, not factoring in immigration, access to hockey, career length, etc. It is also an extremely conservative estimate since immigration rates in Canada have grown steadily since 1950. As a result, Canadian-born players certainly represent a smaller proportion of the Canadian-born population than a half-century ago – they just have a lot more company now.

That similar slice of Canadians – previously playing amongst each other – now plays against the best from at least 15 other nationalities by birth. This includes 31.1% of NHL membership from Europe and 26.1% from the United States in 2019-20 (per quanthockey.com). The validity of an Original Six NHL being more exclusive than today is ridiculous when you consider the enhanced competition from the league’s significant international footprint. Year to year, the league may periodically dilute itself by expansion, but the growth of the full-time player pool lags behind the growth of the available talent worldwide.

We introduced adjusted statistics to bridge this gap, contextualizing counting stats to a neutral environment. We refined Hockey-Reference’s point share methodology, assigning specific value to player contributions, and forming the building block of PPS. Yet, these insightful adjustments cannot account for the seismic improvement in play in a sport enduring for over a century. As a result, our fourth factor in PPS serves as a timeline adjustment to NHL history.

This addition is a Bill James concept, altered considerably in execution. James used birth year as the basis for his adjustment, assigning a fixed positive number relative to the birth year 1800. If two players were born in 1951, for instance, each is granted an identical timeline adjustment, larger than a player born in 1950. In PPS, the timeline adjustment is driven instead by the season a player makes his NHL debut. The more notable discrepancies, however, are that the adjustment is not a fixed figure, but rather a penalty as a percentage of the sum of career, pace and peak value scores. This connects the timeline adjustment to the player’s PPS in terms of the extent of the rollback.

Let’s clarify the calculation by presenting the impact in seasons spanning the NHL’s kickoff through the present day. The “Example Player” is the one debuting in that season with the highest career point total (through 2020-21).


Season #SeasonEraTimeline FactorExample Player
11917-181-10.0%Cy Denneny
131929-301-8.8%Syd Howe
261942-432-7.5%Maurice Richard
381954-552-6.3%Don McKenney
511967-683-5.0%Jacques Lemaire
641980-813-3.8%Paul Coffey
771993-944-2.5%Jason Arnott
902007-084-1.2%Patrick Kane
1022019-2040.0%Cale Makar
1032020-215+0.1%Kirill Kaprizov
Timeline Factor = % penalty applied against sum of PPS career + pace + peak values

Pioneers featuring in the inaugural 1917-18 season, such as Cy Denneny and Georges Vezina, are docked the maximum 10% off their PPS career, pace and peak values. Why 10%? Trial and error. 20% all but eliminated Era 1 players from relevance in the all-time rankings, whereas 5% or less overrepresented players debuting in the first half-century. With each new season, players are penalized slightly less, the factor shrinking by approximately 0.1% each season until arriving at nil for the 2019-20 season. The sliding percentage is based on increments of 1/102, representing the NHL’s 102 seasons at the time of development (2019-20, the end of Era 4). Starting in Era 5, players debuting will receive a positive adjustment of (1/102), continuing the trend.

Of course, quality of competition and the ease in which one can dominate are not perfectly linear trends. The timing of war service, expansion franchises, or migration of European talent to North America, among other factors, are sporadic events. We have to keep in mind, however, that adjusted point shares already use in-season replacement level to establish value, so some of the noise from year to year imbalance balance is already considered. For practical purposes, using a gradual sliding scale from -10% to 0% is a reasonable representation that acknowledges the improvement in quality of competition without disregarding past achievements. Our timeline adjustments are capturing the slow burn of obvious improvement in the standard of play of a period spanning WWI and COVID-19.

PPS Factor #4: Timeline Adjustment

Sum of career value, pace value, and peak value X
(-10% x [102 – Debut Season] ÷ 101)

Debut Season: 1917-18 = 1 … 1966-67 = 50 … 2019-20 = 102 …

Debuting in the NHL's 90th season, Patrick Kane's core PPS value is docked only 1.2%, a long way from the 10% penalty in the NHL's founding season. "Patrick Kane celebrates his goal to make the score 2-0 in Game 6 of the 2015 Stanley Cup Finals." by rchdj10 is licensed under CC BY-NC-ND 2.0

The extent a player’s PPS is reduced, therefore, is a function of two parts: 1. how far back they debuted, and 2. the strength of their three core PPS scores. We’ll illustrate the impact of the timeline adjustment below using comparable players, each debuting in or near the first season of our four defined eras.


PlayerDebut SeasonEraPPS Core ValueTimeline FactorTimeline Adjustment
Ken Randall1917-18115.5-10.0%-1.6
Fern Flaman1944-45215.4-7.3%-1.1
Mickey Redmond1967-68315.9-5.0%-0.8
Boris Mironov1993-94415.9-2.5%-0.4
PPS Core Value = sum of PPS career + pace + peak values; Timeline Adjustment = PPS Core Value x Timeline Factor

In the example, each player’s PPS score – before timeline adjustment and bonus value – is between 15.4 and 15.9. As the season factor decreases over time, Randall (-1.6) receives a larger penalty than Mironov (-0.4) by virtue of debuting 76 years earlier.

The players above entered the NHL decades apart with similar results. Let’s instead compare two players of the same vintage with dissimilar results.


PlayerDebut SeasonEraPPS Core ValueTimeline FactorTimeline Adjustment
Gordie Howe1946-47237.5-7.1%-2.7
Howie Meeker1946-4728.3-7.1%-0.6

Howe and Meeker each debuted in 1946-47 and would become household names in hockey – Howe as one of its greatest players, Meeker as a Leaf forward, turned Member of Parliament, turned TV commentator. While each player’s season factor is -7.1%, Howe’s adjustment is -2.7 to Meeker’s -0.6, a product of their distinct performances in PPS. Howe, in fact, is the 16th-most penalized skater by timeline adjustment. A dominant force whose debut came in only the NHL’s 30th season, his career is the type the adjustment is intended to contextualize.

Given timeline adjustment is a contextual penalty in PPS, this factor would not have a proper “leaderboard.” However, it’s interesting to observe the most affected players of all-time. We won’t look at the timeline adjustment by era as this would give away too much about the final PPS scores. To gain a sense of old-timer adjustment size, the all-time most penalized by position are:

  • Forward: Howie Morenz (debut: 1923-24), -3.3
  • Defenceman: Eddie Shore (debut: 1926-27), -3.0
  • Goaltender: Clint Benedict (debut: 1917-18), -4.0

By design, the timeline adjustments are not excessively punitive. PPS is not intended to dismiss players from the first quarter or half of the NHL’s history. The project to date has focused on neutralizing statistics and extracting value to the extent possible. Imposing harsh downward adjustments to obliterate the results of Era 1 players would be against the spirit of Adjusted Hockey’s purpose. At the same time, it’s not logical to simply ignore glaring improvement in the quality of competition between players born in the 19th and 21st centuries (and all those between). The timeline adjustment factor works smoothly to ensure gradual trends in the development of the sport are captured in a rational way.

Lastly, we’ll check on Jarome Iginla‘s player card, weaving his timeline adjustment into his PPS equation. With a core score of 27.8 and a debut in 1996-97 (-2.2%), Iginla is docked -0.6 on timeline, flagged at the bottom left of his card. This reduces his PPS to date from 27.8 to 27.2, ahead of the potential bonuses to be awarded.

We’re now on the home stretch to bringing PPS together. With four of five factors added, the details of the systematic approach are crystalizing. The final step is to add three bonuses to the mix. The bonus value is designed to capture a player’s career outside the direct contributions of their regular season statistical performance. As a refresh, bonus value consists of the following three streams: 1. Playoff; 2. International; and 3. Award shares.

Let’s move on to the bonus round.

Era Names, Era development concepts, Adjusted GP, Adjusted Yrs, Adjusted PS, Adjusted Pace data, PPS System and Player Card from Adjusted Hockey;
All other data (unless specifically cited) from Hockey-Reference.com.