On Players Evaluation - Part IV (Teams Elo Projections)

On Players Evaluation - Part IV (Teams Elo Projections)

Part I
Part II
Part III

We left our reader at the point where we demonstrated how to produce Elo ratings for hockey teams over season (and over postseason too, if anyone wondered) and how to apply it to the up and coming next games of the rated teams.

However, in its main eparchy, chess, Elo is rarely used to produce single match outcome projections. It's much more popular when used to create a long-term projection, such as the whole tournament, which in chess lasts between five to thirteen rounds, usually.

Therefore, the question arises, shouldn't we try to use our newborn Elo ratings to long-term projections? And the answer is an unambiguous 'Yes!' We can and should create the projections for the team over longer spans such as a seven days ahead, thirty, or even through the end of the season!

How do we do it? Since we computed the Elo ratings for all teams, and we know the schedule ahead of all teams, we can run the Elo expectation on all matchups during the requested span and sum them. And since we assume that each team performs according the expectation, their Elo ratings do not change during the evaluation span.

E_team = Σ(E_match1, E_match2, ... , E_matchn)

All good? No. There is one more finesse to add. The produced expectations will all be calculated in 2-0 span per game, assuming only 2 points are in play in each matchup. However, due to the loser's point it's not so. Therefore on average there are 2 + N_OT/SO / N_total points are handed out during the season in every match (where N_OT/SO is the number of games that get decided in OT or SO). So we need to compute the N_OT/SO value, divide it by two (because there are two teams in each match) and multiply the expectation of each team by this factor. By doing so we receive the reliable Elo expectation, such as one in the table below, as of Jan 2nd, 2017. Spans of 7 days, 30 days and through the end of the season are displayed (games, expected points and total).

Elo ratings for season 2016

#	Team	Div	Elo	Pts	Gin7	Pin7	Tin7	Gin30	Pin30	Tin30	GinS	PinS	TinS
1	Columbus Blue Jackets	MET	2265.22	56	4	6	62	14	23	79	47	79	135
2	Pittsburgh Penguins	MET	2186.57	55	1	2	57	11	16	71	44	65	120
3	Minnesota Wild	CEN	2180.88	50	3	4	54	14	21	71	46	68	118
4	San Jose Sharks	PAC	2137.87	47	3	4	51	14	20	67	45	62	109
5	Washington Capitals	MET	2135.54	49	4	4	53	15	18	67	46	59	108
6	Montreal Canadiens	ATL	2117.99	50	4	5	55	14	18	68	45	58	108
7	New York Rangers	MET	2135.43	53	3	4	57	11	14	67	43	54	107
8	Chicago Blackhawks	CEN	2103.27	51	3	4	55	12	15	66	42	52	103
9	Anaheim Ducks	PAC	2105.41	46	3	4	50	13	18	64	43	55	101
10	Edmonton Oilers	PAC	2092.89	45	4	4	49	14	16	61	44	53	98
11	Ottawa Senators	ATL	2088.34	44	2	2	46	11	11	55	45	52	96
12	Toronto Maple Leafs	ATL	2097.27	41	3	4	45	12	14	55	46	54	95
13	St. Louis Blues	CEN	2066.58	43	2	2	45	12	12	55	44	51	94
14	Boston Bruins	ATL	2079.41	44	4	5	49	15	17	61	43	49	93
15	Carolina Hurricanes	MET	2093.06	39	4	5	44	13	13	52	46	53	92
16	Los Angeles Kings	PAC	2066.68	40	4	4	44	14	16	56	45	52	92
17	Philadelphia Flyers	MET	2079.35	45	3	3	48	12	13	58	43	46	91
18	Calgary Flames	PAC	2076.79	42	4	5	47	14	16	58	43	49	91
19	Tampa Bay Lightning	ATL	2068.90	42	4	4	46	13	14	56	44	48	90
20	New York Islanders	MET	2070.87	36	2	3	39	12	14	50	46	51	87
21	Florida Panthers	ATL	2059.66	40	4	5	45	13	14	54	44	46	86
22	Nashville Predators	CEN	2055.15	38	4	4	42	14	14	52	46	48	86
23	Dallas Stars	CEN	2052.77	39	3	3	42	13	13	52	44	46	85
24	Vancouver Canucks	PAC	2049.05	37	4	5	42	12	15	52	44	46	83
25	Detroit Red Wings	ATL	2033.62	37	3	3	40	13	12	49	45	43	80
26	Winnipeg Jets	CEN	2017.50	37	4	4	41	14	14	51	43	40	77
27	Buffalo Sabres	ATL	2009.45	34	3	3	37	13	12	46	46	41	75
28	New Jersey Devils	MET	1994.66	35	5	4	39	14	12	47	45	37	72
29	Arizona Coyotes	PAC	1921.41	27	3	2	29	12	8	35	45	30	57
30	Colorado Avalanche	CEN	1910.42	25	3	2	27	12	7	32	46	29	54

The N_OT/SO value right now is about 1.124 (i.e. about quarter of all games are decided past the regulation).

So you know what's good for the people?

But the people consists of men...

Iconic Soviet movie

The team projection leaves us wanting more. After all, don't we want to be able to evaluate individual players and factor it somehow in the projection to reflect the injuries and other reasons that force top players out of the lineups? Stay tuned.

To be continued...