And how would you like to regress today, Mr. Bond?

Cam Charron
November 09 2011 01:32PM

Probably the most unfortunate thing about the start of the new NHL season, other than all the hope and promise that accompanies your new team with its new additions, is all the hope and promise that comes when a team manages to string together a few wins in October.

The PDO of the Toronto Maple Leafs (save percentage plus shooting percentage) has slumped from about 108 after the first two weeks to 101.2 after last night's loss to the Florida Panthers. The offense, once clicking on all cylinders with Phil Kessel leading the way, has now scored just a single goal in the last two games. The goaltending, once an area not of concern with the play of James Reimer, has fallen to new lows as Jonas Gustavsson and Ben Scrivens, to put it quite plainly, haven't given the Leafs what they needed since Reimer has gone down.

Equally disconcerting is that when Toronto were winning games, they were close victories, which is an unsustainable way of winning. Given how much luck is required to win a close hockey game, eventually, that regresses as well. This was explained by Bill James in something he called the Pythagorean Expectation, and it introduces the theory that a hockey team can really only control two things: the number of goals scored, and the number of goals scored against. The time these goals occur, and in what order, balances out over the course of a long season.

Here is the relatively simple formula for calculating a team's expected winning percentage:

                    Goals For ^ 2                    
 ( Goals For ^ 2 ) + ( Goals Against ^ 2 )

This is something previously discussed by Chemmy, but with the Leafs having fought off the PDO monster with two-straight blowout defeats, they now face the Pythagorean monster. The team's 9-6 record is disproportionate to its minus-5 goal differential.

First, let's look at the current Eastern Conference standings:

Rank Eastern GP Pts Wins
1 Pittsburgh 15 21 9
2 Toronto 15 19 9
3 Washington 13 18 9
4 Buffalo 14 18 9
5 Philadelphia 14 18 8
6 Florida 14 17 7
7 NY Rangers 13 17 7
8 Tampa Bay 14 16 7
9 New Jersey 13 15 7
10 Ottawa 15 15 7
11 Carolina 15 13 5
12 Winnipeg 15 13 5
13 Boston 13 12 6
14 Montreal 14 12 5
15 NY Islanders 12 10 4

Now, let's look at the Eastern Conference standings, with wins adjusted for Goals For and Against:

Rank Eastern GP Wins xW GF GA
1 Pittsburgh 15 9 9.5 45 34
2 Buffalo 14 9 8.7 42 33
3 Philadelphia 14 8 8.7 56 44
4 Boston 13 6 8.3 40 30
5 Washington 13 9 8.2 50 38
6 NY Rangers 13 7 7.7 35 29
7 Florida 14 7 7.4 39 37
8 Toronto 15 9 6.7 46 51
9 Tampa Bay 14 7 6.7 44 46
10 Montreal 14 5 6.2 35 39
11 Ottawa 15 7 6.0 45 55
12 New Jersey 13 7 5.9 33 36
13 Winnipeg 15 5 5.7 40 51
14 Carolina 15 5 5.3 37 50
15 NY Islanders 12 4 4.1 25 35

( column xW denotes "expected wins")

This chart doesn't mean that math hates the Leafs, or that Leafs Nation hates the Leafs, but shows that the team's record, thanks to its PDO and its goal differential, is slightly deceiving. The good news (sort of) about the goal differential is that prior to the team's two blowouts, the team had a +6 goal differential and would have been tied for Florida with 7.4 xW.  The bad news is that those two games happened, and, since they happened, they fit into the measure of a team's overall ability.

Simply put, er, the Leafs simply have to score more goals, and start allowing fewer goals. They will win more hockey games this way. Regression has hit the Leafs PDO already and the fanbase are feeling the effects. Hopefully, the goal differential fairies don't all sting in one blow as well.

 

*-second chart updated to include actual number of wins

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Cam Charron is a BC hockey fan that writes about hockey on many different websites including this one.
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#1 kidkawartha
November 09 2011, 01:42PM
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Leafs sneak into 8th and the Habs and Sens miss out? I can dig it.

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#2 Chemmy
November 09 2011, 01:46PM
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The data says the Leafs aren't going to win the division. So does common sense.

The data says though, that the Leafs are holding the 8 seed despite horrific goaltending. That's got to be cause for optimism.

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#3 John K
November 09 2011, 01:59PM
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Awesome title and solid article. I'd like some background on the Bill James 'Pythagorean Expectation', however.

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#4 VRN
November 09 2011, 02:05PM
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Technically, shouldn't Tampa be 8th, since they have the same number of expected wins in fewer games played?

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