Total Hockey Rating (THoR) results through end of 2013By Michael Schuckers | May 13th, 2013 | Category: Empirical Sports Blog, Hockey, MIT SSAC, Uncategorized
The THoR page (http://www.statsportsconsulting.com/thor) has the latest set of Even Strength (EV) and All (EV/PP/PK) ratings for players that appeared in over about 25 games in the past two seasons. What is new here is that we have added a new model for EV and PP and PK to the model to our EV model. The model for all events includes all of the terms in the EV model (see the THoR page) such as Quality of Teammates, Score Effects, and Zone Starts and adds terms for the one man and two man advantages as well as differential terms for a zone start (ZS) for each of these situations.
The data used here is for the complete 2011-12 and 2013 seasons. In total there are n= 476614 plays that were recorded, 399171 of those were at even strength(5v5 or 4v4). All of the estimated values here are based upon an average per play performance for these two seasons. We estimate that home ice over this period was worth about 0.31 goals per game. This estimate comes from the effect on each play extrapolated to approximately 244 events recorded per game. This is consistent with other estimates from recent seasons. As we have noted previously (here), a ZS at even strength is worth about five times what home ice is worth to a given play. Another way to think of an even strength ZS is that moving from starting a shift in the neutral zone to starting in the offensive zone is equivalent to replacing an average player on a given line with a top 10 player (e.g. a Johnathon Toews or a Daniel Sedin).
The score effect term in our models is only present if the score differential is more than two goals. As other hockey analytics folks have noted, teams that are ahead tend to play differently. Empirically, we find that this is true and that the effect grows as the score differential grows.
The Top 10 Players in these ratings are: E. Staal (5.55 wins over average) , D Sedin (5.38) , S. Weber (4.92) A. Kopitar (4.81) , C Kunitz (4.74) , J Eberle (4.74) , E. Karlsson ( 4.73), J Toews (4.49), L Couture (4.16) , D Doughty (3.99). P. Datyzuk finishes just below D. Doughty and his THoR rounds to the same number of wins 3.99. For the even strength only ratings the top ten was the following: A. Kopitar, E. Staal, E. Karlsson, P. Bergeron, J. Toews, L. Couture, H. Sedin, C Kunitz , D. Hamhuis and R. Getzlaf.
The number of wins over an average player at their position for which they are responsible in an 82 game season. These values account for the amount of time that players played. Thus, E. Staal is the top because he is near the top in per play value but because he plays so much he is the most valuable player in these rankings. On a per events on the ice, D Sedin is better than E Staal but E Staal contributes more total because he was on the ice for more action over the past two years. Defensemen do better in the THoR ratings this time around as we have adjusted players by average impact at their respective positions. Note that this means that THoR finds than average forwards have a greater impact than average defensemen on generating goal differential. Note that to get wins over replacement you can add approximately half a win to each player, e.g. S. Weber would be worth about 5.42 wins over a replacement D.
Sidney Crosby is not in our top 10 or top 20 for this period. The story there is that Crosby has not been in enough games. We are ranking players based upon their total contributions over the past two seasons. It’s not that Crosby has not been good (or dominant as he was for significant portions of the 2013 season) when he has played, but rather the model penalizes Crosby and others for not playing. Ridge regression, the statistical method we are using, weights toward zero, or shrinks, our estimated values this especially impacts those with fewer games played. We do this to deal with the flucutations in player ratings due to small sample sizes and multicollinearity which here means consistently playing with the same teammates..
At the team level of the teams still in the hunt for the 2013 Stanley Cup, Boston has 3, Chicago has 5 (with P Kane sitting at 105), Detroit has 3 (with J Franzen at 102), LA has 6, the Rangers have 1, Ottawa has 2, Pittsburgh has 5 (not including Crosby), and San Jose has 5.