There are quite a few players coming from the AHL that are off to great starts this season, like Edmonton's Gilbert Brule, Matt Moulson of the Islanders and Jason Demers of San Jose. Are these guys the real deal, or should we expect them to cool off as the season progresses?
The American Hockey League, which dates back to the late 1930s, is North America's primary professional hockey league, after the NHL. This is where NHL teams send their young players to develop, and where veteran players extend their careers and work towards earning another chance. Many NHL Hall of Famers played in the AHL, some of them for only a season or two, and others for extended periods, like Bun Cook and "the China Wall" Johnny Bower. It stands to reason that a good understanding of how to translate statistics from the AHL to the NHL can provide valuable insights into today's hot young stars.
Enter League Equivalencies. The AHL is ideal for league equivalency research because of the high number of data points. Since the lockout, there have been over 500 players that have played at least 20 games in both leagues. Thanks to all of this data, we can take the first step to improving the precision of our translations by taking a closer look at the observation bias that suggests that the translation factors are going to be different depending on whether a player is moving from the AHL to the NHL, or vice versa.
#: Number of data points (players)
AHLG/AHLA: Average AHL goals/assists per game
NHLG/NHLA: Average NHL goals/assists per game
GFACT/AFACT: Goal/Assist Translation factor
Group # AHLG NHLG GFACT AHLA NHLA AFACT
AHL-to-NHL 494 0.23 0.11 0.47 0.36 0.17 0.48
NHL-to-AHL 209 0.26 0.09 0.38 0.36 0.15 0.41
Same Season 170 0.26 0.09 0.35 0.42 0.15 0.36
According to this chart, players moving from the AHL to the NHL retain a noticeably higher percentage of both their goals and their assists than those moving in the opposite direction. Despite scoring at roughly the same level in the AHL for both goals and assists, the players coming from the AHL do better in the NHL than those leaving. I suppose that stands to reason, because their poor NHL performance is probably why they're leaving in the first place.
Given that the average age of a player going from the AHL to the NHL is 23.1, and the average age of a player going from the NHL to the AHL is 25.5, can the 2.4-year age gap explain the difference between the two translation factors? If so, we can break our translation factors down by age, and take the next step towards greater precision.
AHL2NHL NHL2AHL Same Season
Age # GFact AFact # GFact AFact # GFact AFact
19 5 1.06 0.67 3 0.75 0.64 - -- --
20 64 0.60 0.53 4 0.25 0.37 17 0.56 0.40
21 84 0.52 0.59 20 0.52 0.51 31 0.35 0.40
22 93 0.51 0.51 27 0.28 0.38 28 0.39 0.40
23 68 0.43 0.44 15 0.46 0.47 22 0.35 0.43
24 54 0.42 0.41 23 0.36 0.46 24 0.33 0.37
25 33 0.47 0.45 16 0.29 0.32 10 0.33 0.17
26 28 0.30 0.36 19 0.40 0.32 5 0.29 0.39
27 33 0.38 0.41 25 0.37 0.35 10 0.32 0.30
28 17 0.33 0.32 8 0.51 0.50 12 0.28 0.29
29 7 0.28 0.25 21 0.39 0.37 3 0.31 0.19
30 5 0.51 0.44 10 0.26 0.36 4 0.21 0.22
31 3 0.54 0.27 7 0.36 0.32 1 0.25 0.16
32 - -- -- 4 0.49 0.41 - -- --
33 - -- -- 2 0.59 0.77 2 0.14 0.33
For players going from the AHL to the NHL we can see, despite relatively small sample sizes, that the translation factors for goals and assists drop significantly roughly between ages 20-22 and again at roughly age 28 and up, but are pretty level in-between.
The picture is a little cloudier when players are going from the NHL to the AHL, where the goal translation factor seems to fluctuate wildly across the curve. The assist translation factor is a little smoother, however, and drops off at age 24. Looking at those who played in both leagues in the same season, the translation factors are relatively flat until dropping off around age 27. Very interesting.
When we studied Victor Hedman and the Swedish Elite League last week, we applied a single, common translation factor for all players regardless of age. This time, we can enjoy the higher accuracy inherent in using age-specific translation factors instead. Here are the AHL to NHL translations for all of today's NHL players that have at least 4 points so far this season, and played 20 games or more in the AHL last season. To complete the picture, I added their 2008-09 NHL totals (if any) to their age-specific translated AHL totals.
Age Player 2009-10 Team GP G A PTS
20 Artem Anisimov NY Rangers 81 22 23 45
23 Alex Goligoski Pittsburgh 71 7 21 28
21 Patric Hornqvist Nashville 77 11 16 27
25 Matt Moulson NY Islanders 61 11 12 23
20 T.J. Galiardi Colorado 77 9 10 19
20 Jason Demers San Jose 78 1 16 17
21 Gilbert Brule Edmonton 50 9 7 16
24 Jonathan Ericsson Detroit 59 2 8 10
(Minimum 4 points in 2009-10 season, played 20+ games in the AHL in 2008-09).
In Artem Anisimov the New York Rangers have a legitimate 20-goal forward who could score between 40 and 50 points this season. Pittsburgh has a solid 30-point defenseman in Alex Goligoski, but some of these other players could just be off to hot starts and it might take a couple of seasons before they can score at their current levels on a consistent basis.
For greater precision in league equivalencies, we can separate our translation factors between players going from one league to the NHL, and for those making the return trip. If we lack the data points to do so, we'll adjust the translation factor by a rate similar to what we see in the AHL.
To improve the precision even further, we can break out the translation factors by age and plot it along an age curve, and apply the appropriate age-specific translation factor to each player. As we can see in the AHL, players from ages 20-22 are going to retain a lot more of their scoring levels when moving to the NHL than someone in their mid-20s or older. In a future article we'll take a closer look at the effect age has on scoring.
Thanks to a more sophisticated look at league equivalencies and translation factors, we have a better idea for which of today's former AHLers will most likely continue their hot scoring rate. Artem Anisimov could be just what the Rangers needed for secondary scoring, but don't be surprised to see Brule, Moulson and Demers cool off.
Robert Vollman is an author of Hockey Prospectus.
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