How age, shooting percentage and ‘puck luck’ factor into future performance

Monday November 7th, 2016

This work was completed as part of a larger project on age profiles and could not have been done without the valuable assistance, data and support of HockeyTech

At the beginning of the 2012-13 season, Kris Versteeg was a highly respected two-way forward whose resume included four 20-goal seasons and a Stanley Cup championship. There was little reason to think the 26-year-old didn’t have more great years ahead of him. As a result, the Florida Panthers rewarded him with a 4-year contract extension at an average annual value of $4.4 million.

The decision may have seemed reasonable to most pundits at the time, but then age and injuries took their toll and Versteeg bounced around among four different teams over the next four seasons.

Now 30, the former star came back to the NHL via a tryout contract in September after failing a physical with SC Bern in the Swiss League.

While injuries are difficult to predict, age comes for us all. Exactly when can vary among players, but there are some patterns to how players age, and it’s a mistake to believe there’s a “one size fits all” approach.

More skilled players, for example, tend to peak later and decline more slowly.

What complicates these patterns are the now widely recognized fluctuations in shooting percentages that can lead to players having abnormally good or bad seasons just due to "puck luck." For example, many analysts will often take note if a player with a career average shooting percentage of 10% suddenly scores 30 goals one season based on 20% shooting. Chances are his shooting percentage will drop the following year and he won’t repeat those statistics.

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This concept is what statisticians call “mean reversion”, which is a fancy way of saying that, in the long run, everything tends toward an average number even if there are short-term ups and downs.

Moreover, it’s not just a player’s own shooting percentage that can influence his point totals. Those of his linemates also have a big impact on the number of assists he gets. If you make a bunch of outlet passes that end up being second assists on your linemates’ lucky goals, you’re likely a good candidate for a disappointment the next season.

It’s all well and good to acknowledge these effects, but it’s another to quantify their impact accurately.

In order to do that, we looked at every single forward who played more than half a season since 2005-06 and tracked how his offensive production changed the following season.

We then considered how these changes were influenced by things such as age and mean reversion in individual and linemate shooting percentages (as well as a lot of other variables).

As it turns out, analysts who assume a player’s shooting percentage will always revert to his career average are missing a very important detail, namely that a player’s shooting percentage follows its own age curve.

Younger players tend to have lower shooting percentages that improve as they gain pro experience. Conversely, as players start to decline overall, one of the things that also goes is their shooting ability.

This means that a 23-year-old who shows a sudden jump in his shooting percentage may in fact be able to sustain that higher level in subsequent years. Equally, a 29-year-old who is performing at below his career average shouldn’t automatically be expected to rebound next season.

Now to the fun part.

We took every forward who played more than 41 games in 2015-16 and used our model to make predictions of what we could expect if he played a full 82-game season in 2016-17 (and yes we’re aware that guys will get injured, but good luck predicting that).

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Below are predictions for four kinds of players:

(i) Stagnant Youth - Young players who won’t improve because their performance has been unsustainable

(ii) Breakout Players - young players who had bad luck previously and so will get the double kick of age and mean reversion

(iii) Veterans With Upside - older stars who will bounce back

(iv) Faded Stars - veterans who are in full decline mode

(Note that, because our model excludes guys with only one season under their belt, we’re not making predictions for last year’s rookie crop, which included some standout talents. So while we don’t doubt that Connor McDavid will contend for the scoring title while resurrecting the Oiler franchise, we’re not predicting an actual number for him).

Because age is so critical in this analysis, our model is kinder to younger players. So, for example, all of the players on our “Stagnant Youth” list are still going to have very good, and in some cases excellent, seasons.

For example, Artemi Panarin and Johnny Gaudreau will remain great; however, all signs point to last season’s performance having benefitted from some “puck luck”. So while they may improve simply due to additional experience, that effect will be counteracted by some mean reversion.

THE STAGNANT YOUTH

Name

2015-16 Age

2015-16 GP

2015-16 Pts

2016-17 Predicted points

A. Barkov

20

66

59

61

E. Kuznetsov

23

82

77

66

A. Panarin

23

80

77

70

J. Gaudreau

22

79

78

74

A. Wennberg

20

69

41

42

V. Trocheck

22

76

53

52

J.T. Miller

22

82

43

38

M. Scheifele

22

71

61

66

A. Duclair

20

81

44

40

N. Kucherov

22

77

66

66

The flipside of this is that younger players who underperformed last season – guys like Elias Lindholm, David Pastrnak, Nathan MacKinnon and Ryan Nugent-Hopkins – are poised for big jumps. They won’t necessarily surpass their “stagnant” peers, but just as most pundits are overestimating the previous group’s performance for this season, the “Breakout Youth” are heading in the opposite direction and so are generally being underrated.

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THE BREAKOUT YOUTH

Name

2015-16 Age

2015-16 GP

2015-16 Pts

2016-17 Predicted points

E. Lindholm

20

82

39

56

D. Pastrnak

19

51

26

51

N. MacKinnon

20

72

52

68

R. Nugent-Hopkins

22

55

34

59

S. Bennett

19

77

36

44

T. Toffoli

23

82

58

63

S. Monahan

20

81

63

69

T. Hertl

21

81

46

51

R. Fabbri

19

72

37

47

N. Ehlers

19

72

38

48

Meanwhile, older players will live out a simple fact that everyone should know: age is cruel, punishing, and rarely forgiving.

Finding vets with upside isn’t easy. And when you do, the reason usually is that a former elite talent like Eric Staal had a horrifically bad 39 point season that is expected to translate into an adequate 44 point campaign this year. Staal is never going to be the 30 goal 70 point talent he once was, but he’s not ready for his next career just yet.

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In order to get a top 10 list for this group, we ended up mostly with guys who were expected to hold the line rather than improve. So “upside” for a vet means simply staving off his inevitable decline for one more season.

VETERANS WITH UPSIDE

Name

2015-16 Age

2015-16 GP

2015-16 Pts

2016-17 Predicted points

E. Staal

30

83

39

44

D. Brown

30

82

28

32

M. Perreault

27

71

41

51

J. Pominville

32

75

36

42

D. Perron

27

71

36

43

N. Foligno

27

72

37

43

P. Hornqvist

28

82

51

52

P. Kessel

27

82

59

60

T.J. Oshie

28

80

51

53

P. Berglund

27

42

15

30

Last of all, our Faded Star group is made up of the types of players we might expect to see on a team’s unprotected list for June’s expansion draft. These are exactly the kinds of players their current teams would know are done and who an expansion team might optimistically imagine will have a renaissance in Las Vegas.

THE FADED STARS

Name

2015-16 Age

2015-16 GP

2015-16 Pts

2016-17 Predicted points

H. Sedin

34

74

55

48

J. Ward

34

79

43

34

D. Sedin

34

82

61

51

C. Soderberg

29

82

51

42

L. Stempniak

32

82

51

42

B. Wheeler

29

82

78

70

J. Spezza

32

75

63

61

T. Vanek

31

74

41

37

S. Hartnell

33

79

49

43

 
Both Sedins, who have done everything as the identical twins they are so far,  appear to be joining each other for a permanent hiatus from elite scoring. The same goes for Scott Hartnell, who has more than 300 career goals and three consecutive 20-plus goal seasons. And while Thomas Vanek has gotten off to a strong start in Detroit early this season, we’d be very surprised if it lasts.

Predicting the future isn’t an easy business. But if you’re making player personnel decisions for any NHL team - or assembling an expansion team in Las Vegas - understanding the complex interaction between the dual phenomena of age and mean reversion is one way of making better predictions.

The Department of Hockey Analytics employs advanced statistical methods and innovative approaches to better understand the game of hockey. Its three founders are Ian Cooper, a lawyer, former player agent and Wharton Business School graduate; Dr. Phil Curry, a professor of economics at the University of Waterloo; and IJay Palansky, a partner at the law firm of Armstrong Teasdale, former high-stakes professional poker player, and Harvard Law School graduate. Please visit us online at www.depthockeyanalytics.com

Jordan Hill is a masters student in the economics program at the University of Waterloo and a former Jr. A hockey player.

HockeyTech (www.hockeytech.com) is a worldwide leader in providing hockey-related technologies, analytics and information services. HockeyTech was founded in 2013 by Stu Siegel (technology entrepreneur and former Florida Panthers Managing Partner/CEO) through a series of acquisitions. While HockeyTech is a new corporate identity, its brands have been providing cutting-edge solutions to the hockey world since 1998.  HockeyTech brands include RinkNet, ISS Hockey, HockeyTV Website, LeagueStat, and NEXT Testing.

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