Wednesday, July 29, 2009

Do Defensemen influence Save Percentage?

[Note: this methodology is similar to a previous analysis of replacement level: http://www.behindthenet.ca/blog/2008/04/replacement-level-how-many-wins-do.html. It is obvious that teams do worse when their top players are out of the lineup, but it's not clear what suffers.]

In order to answer this question, I made a list of defensemen over the last four seasons who averaged more than 22 minutes per game and played between 20 and 70 games in a given season. 22 minutes of TOI corresponds approximately to the 60th-best defenseman, which means that the group of subjects includes mostly 1st and 2nd defensemen.

I then counted up the number of even-strength goals and shots against when each defenseman was in the lineup and when he was not dressed. I further split the defensemen into those whose +/- was better than the team's overall +/- (on a per minute basis). Presumably the group with the "Better +/-" would have more of an impact on even-strength defensive zone play.

The results:

IN OUT
GP G/GP S+G/GP SVPCT GP G/GP S+G/GP SVPCT DELTA
N=28 Better +/- 1610 1.85 21.48 914.0 686 2.04 21.94 907.2 5.8
N=25 Worse +/- 1229 1.89 22.20 915.1 821 1.89 22.00 914.2 0.9

The assumption here is that during a given season, a player's aggregate group of teammates, including the goalie, will be basically unchanged whether he's in the lineup or not. Similarly, his team's aggregate group of opponents is assumed to be the same whether he's in the lineup or not.

While the defensive difference with the "Worse +/-" defensemen out of the lineup was negligible, the teams of the "Better +/-" defensemen allowed 15.5 fewer goals per 82 games when they were playing. One-quarter of this change was due to reducing the volume of shots allowed, but the rest is due to better save percentage.

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Tuesday, July 14, 2009

Goaltender Pairs and 5v5 Rebounds

Here are all of the 2008-09 Goaltending pairs where shot totals were roughly even. Draw your own conclusions...





























NameTeamSHREB%<2REB%<4SPCT
Jonas Hiller ANH8484.127.9932
J. Giguere ANH8813.515.78913
Kari Lehtonen ATL10863.686.07923
Johan Hedberg ATL6213.546.11909
Tim Thomas BOS12663.555.92940
Manny Fernandez BOS6194.686.78927
N. Khabibulin CHI8624.527.54932
Cristobal Huet CHI7603.945.92917
Peter Budaj COL11544.596.06906
Andrew Raycroft COL6503.386.61909
Ty Conklin DET7793.977.7920
Chris Osgood DET8945.256.48904
Tomas Vokoun FLA14634.988.2935
Craig Anderson FLA7264.266.74928
Jonathan Quick LA8753.085.71923
Erik Ersberg LA4713.185.09912
Carey Price MON11153.765.91921
Jaroslav Halak MON8143.436.38923
Scott Clemmensen NJ8693.795.06927
Martin Brodeur NJ6295.086.67934
Pekka Rinne NSH11734.176.64927
Dan Ellis NSH6784.276.48918
Yann Danis NYI6953.455.75922
Joey MacDonald NYI11684.15.99906
Alex Auld OTT8294.226.75920
Brian Elliott OTT6013.495.65920
Mike Smith TB8833.855.77929
Karri Ramo TB4983.217.22913

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Goaltender Rebound Percentage Leaders

In his work on Shot Quality, Alan Ryder noted that shooting percentage is extremely high on rebounds. That is, in the two seconds following another shot. The overall save percentages for 2008-09:



Overall1-2 s3 s4 s
919694807892

After four seconds, shooting percentages are in the low-to-mid 900s. So it is significant to look at what percentage of a goalie's shots are rebounds allowed less than 2, 3 and 4 seconds after a previous shot. Here are the league "leaders":












GoaliePCT<2sPCT<3sPCT<4s
EVGENI NABOKOV5.5267.61
MIIKKA KIPRUSOFF5.336.248.25
CAM WARD5.316.387.09
CHRIS OSGOOD5.255.596.48
MATHIEU GARON5.195.736.55
MICHAEL LEIGHTON5.166.257.06
MARTIN BRODEUR5.085.726.67
TOMAS VOKOUN4.986.638.2
MANNY FERNANDEZ4.685.816.78
PETER BUDAJ4.595.376.06

And at the other end:












GoaliePCT<2sPCT<3sPCT<4s
CHRIS MASON3.254.425.96
STEVE MASON3.244.436.22
KARRI RAMO3.215.227.22
ERIK ERSBERG3.184.675.09
JONATHAN QUICK3.083.775.71
JASON LABARBERA34.65.61
RYAN MILLER2.843.845.76
BRENT JOHNSON2.693.924.9
MARTIN GERBER2.63.94.72
JOSH HARDING1.793.585.67

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Monday, June 1, 2009

New Puck Prospectus Post: The Right Guy in Goal

http://puckprospectus.com/article.php?articleid=160

"With an unproven goalie, teams can not tolerate a losing streak, so newly-arrived goaltenders have to play well immediately in the NHL. The difference between an NHL All-Star and a fringe goaltender is approximately one goal every other game. It doesn't matter that it might take 60 or 70 games to tell whether a goaltender has a true talent save percentage of .910 or .900 - if he plays poorly in his first 10 or 20 games, he gets sent down and somebody else gets a chance."

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Wednesday, April 29, 2009

Shooting Percentage by Location of Directed Shot

Here's the save percentage by right- and left-handed goalies during the 2008-09 season:

I'll admit that I'm not completely sure what's interesting about this data - I have it for every goaltender and every shooter - so if you've got a good idea, send it my way.

Update: Hockey Numbers was all over this back in 2007. The 2006-07 data is no longer available, oddly enough.

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Friday, April 24, 2009

2008-09 5v5 Goaltender Performance

Last year, I posted my methodology for calculating the quality of shots faced by a goaltender, along with the results of this analysis.

The 2008-09 results are below (minimum 700 minutes played at 5v5). The last column, DELTAGAA, shows how much lower a goaltender's Goals-Against-Average was than we would expect it to be given the shots he faced. Henrik Lundqvist, Tim Thomas and Jonas Hiller are the only goaltenders who appear in the Top 10 both this year and last year.

At any rate, here are the top 10:

NAME GP SPCT GAA ExSPT ExGAA DELTAGAA
TIM THOMAS 54 937 1.87 911 2.64 -0.77
NIKOLAI KHABIBULIN 42 927 1.94 902 2.64 -0.70
ROBERTO LUONGO 54 931 1.90 906 2.59 -0.69
HENRIK LUNDQVIST 69 913 2.38 890 3.00 -0.63
TOMAS VOKOUN 59 931 2.25 913 2.84 -0.59
KARI LEHTONEN 46 917 2.73 900 3.29 -0.56
JONAS HILLER 46 927 1.90 906 2.46 -0.56
MARTIN BRODEUR 31 930 1.90 912 2.38 -0.49
CRAIG ANDERSON 31 922 2.62 909 3.09 -0.47
MANNY FERNANDEZ 28 921 2.18 905 2.64 -0.45

Full stats for this season and last available at: http://www.behindthenet.ca/2008/5_on_5_goalie_shot_quality.php?sort=10

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Sunday, June 15, 2008

2007-08 5v5 Goaltender Performance (Full Season)

I finally ran the full-season's worth of shot quality/goaltending statistics (see Mid-Season stats.) There was some discussion over at James Mirtle's site, with some people claiming that Evgeni Nabokov was deserving of the Vezina Trophy - and not Martin Brodeur. The stats don't bear that out:


Nabokov Expected Save PCT 909, Actual 908 - GAA 0.03 higher than average goaltender
Brodeur Expected Save PCT 906, Actual 920 - GAA 0.34 *lower* than average goaltender

Brodeur faced tougher shots than Nabokov, and did a way better job of stopping them. There's no way to argue from a shot quality perspective that Nabokov deserves the award.


Here's the rest of the league, minimum 20 GP:


GP TOI SOG GA SPCT GAA EGA ESPT EGAA DELTAGAA
DUBIELEWICZ20 787:01 394 31 921 2.36 41.1 895 3.13 -0.77
LUNDQVIST 72 3063:24 1201 99 917 1.94 137 885 2.68 -0.74
GIGUERE 58 2287:15 1001 65 935 1.71 92.97 907 2.44 -0.73
HILLER 23 863:21 354 27 923 1.88 37.02 895 2.57 -0.7
FLEURY 35 1285:49 614 41 933 1.91 53.92 912 2.52 -0.6
THOMAS 57 2465:18 1186 83 930 2.02 105.8 910 2.58 -0.56
CONKLIN 33 1311:57 714 47 934 2.15 58.5 918 2.68 -0.53
BRYZGALOV 64 2578:31 1266 91 928 2.12 112.3 911 2.61 -0.5
PRICE 41 1669:29 837 63 924 2.26 75.77 909 2.72 -0.46
LEHTONEN 48 1953:15 1066 88 917 2.7 102.2 904 3.14 -0.43
HUET 52 2170:39 1013 77 923 2.13 91.53 909 2.53 -0.4
BRODEUR 77 3392:35 1386 110 920 1.95 129.5 906 2.29 -0.34
LEGACE 66 2616:37 1084 88 918 2.02 102.4 905 2.35 -0.33
HASEK 41 1587:27 545 42 922 1.59 50.68 907 1.92 -0.33
ELLIS 44 1584:18 805 62 922 2.35 70.76 912 2.68 -0.33
TELLQVIST 22 871:55 413 33 920 2.27 37.57 909 2.59 -0.31
KHABIBULIN 50 1943:04 850 77 909 2.38 86.75 897 2.68 -0.3
OSGOOD 43 1728:03 663 58 912 2.01 66.61 899 2.31 -0.3
AULD 32 1199:26 520 42 919 2.1 47.57 908 2.38 -0.28
VOKOUN 69 2910:13 1510 122 919 2.52 134.5 910 2.77 -0.26
LUONGO 73 2908:45 1318 103 921 2.12 115.7 912 2.39 -0.26
GERBER 57 2248:37 1086 94 913 2.51 103.2 905 2.75 -0.24
BIRON 62 2427:39 1241 95 923 2.35 103.5 916 2.56 -0.21
DIPIETRO 63 2631:01 1173 106 909 2.42 114.4 902 2.61 -0.19
LALIME 32 1267:26 561 54 903 2.56 57.76 897 2.73 -0.18
NIITTYMAKI 28 938:43 474 45 905 2.88 47.46 899 3.03 -0.16
THEODORE 53 2243:30 967 87 910 2.33 92.65 904 2.48 -0.15
LABARBERA 45 1721:56 945 86 908 3.00 90.3 904 3.15 -0.15
TOSKALA 66 2720:58 1201 111 907 2.45 116.6 902 2.57 -0.12
KIPRUSOFF 76 3087:15 1379 118 914 2.29 123.7 910 2.40 -0.11
WARD 69 2718:41 1233 113 908 2.49 117.6 904 2.60 -0.1
LECLAIRE 54 2075:24 880 67 923 1.94 70.49 919 2.04 -0.1
TURCO 62 2556:30 1022 91 910 2.14 94.91 907 2.23 -0.09
MILLER 76 3130:07 1399 122 912 2.34 125.8 910 2.41 -0.07
BUDAJ 35 1405:13 587 52 911 2.22 52.53 910 2.24 -0.02
BACKSTROM 58 2441:35 1110 90 918 2.21 89.42 919 2.20 0.01
NABOKOV 77 3266:15 1190 109 908 2 10 7.49 909 1.97 0.03
NORRENA 37 1359:34 548 57 895 2.52 53.55 902 2.36 0.15
HARDING 29 1141:15 578 54 906 2.84 51.01 911 2.68 0.16
RAMO 22 954:17 453 46 898 2.89 43.27 904 2.72 0.17
MASON 51 1902:51 850 86 898 2.71 80.27 905 2.53 0.18
SABOURIN 24 854:58 383 38 900 2.67 35.36 907 2.48 0.19
KOLZIG 54 2292:20 929 98 894 2.57 89.88 903 2.35 0.21
SMITH 34 1433:34 597 64 892 2.68 58.21 902 2.44 0.24
ROLOSON 43 1670:23 795 79 900 2.84 71.72 909 2.58 0.26
EMERY 31 1205:08 505 52 897 2.59 46.44 908 2.31 0.28
GARON 47 1848:13 882 87 901 2.82 78.14 911 2.54 0.29
HEDBERG 36 1384:59 676 73 892 3.16 64.26 904 2.78 0.38
HOLMQVIST 47 1932:04 760 91 880 2.83 68.73 909 2.13 0.69
TOIVONEN 23 842:20 359 51 857 3.63 38.76 892 2.76 0.87

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Monday, December 24, 2007

2007-08 4v5 Goaltender Performance

Scoring rates go way up on the power-play, making it a goaltender's toughest assignment. (Ray Emery fighting Andrew Peters doesn't count.) To quantify the difference, here's the same plot as we had for 5-on-5 play, except for 5-on-4:



As you can see, the high-scoring zone is much larger than it is for even-strength play. You can also see that teams don't take a lot of shots from tough angles (I excluded any quadrants with fewer than 10 shots in the last six seasons, resulting in some blank zones). So not only is it easier to score from a given spot on the ice, teams also take more high-probability shots, and average save percentages drop from 915 to 877.

I've reproduced the same chart as in the previous post, showing which goalies reduce their 4v5 goals-against-average by the most. Here we have a minimum of 30 minutes played, so one or two goals can skew the results considerably. Henrik Lundqvist again comes out near the top - is he really that good? Or do MSG scorers consistently report that the puck is shot from closer than it really is? [That's a subject for another post.]

PLAYERGPTOISOGGASPCTGAAEXGAEXSPCTEGAADELTAGAA
MIKESMITH1262:555549273.818.318487.92-4.11
MATHIEUGARON1888:587569204.0410.88557.30-3.25
FREDRIKNORRENA1578:017049423.078.218826.31-3.23
MARTYTURCO25131:09124129035.4818.68498.55-3.06
JONASHILLER840:564249045.865.88618.50-2.63
HENRIKLUNDQVIST31160:05144158955.6221.98478.21-2.59
CHRISOSGOOD19105:438079123.9711.58556.55-2.58
MIKAELTELLQVIST1046:044849165.205.858787.61-2.40
CURTISSANFORD836:563939234.874.398877.13-2.25
TOMASVOKOUN32179:50179179055.6723.48697.82-2.14
BRENTJOHNSON958:275849314.106.068956.22-2.11
NIKOLAIKHABIBULIN25143:34126158806.2619.98418.32-2.06
HANNUTOIVONEN1052:554258805.666.598437.47-1.80
MARTINBRODEUR30158:20172188956.8222.68688.56-1.74
JASONLABARBERA2296:47113148768.6716.685210.3-1.66
PASCALLECLAIRE23121:46132148936.8916.98718.37-1.47
MARCDENIS1037:043248756.474.88507.76-1.29
EVGENINABOKOV35165:43120138914.7016.58625.99-1.28
MARTINGERBER24150:51120138915.1716.08666.37-1.20
CAREYPRICE1785:471151586910.416.585611.5-1.07
JOHANHOLMQVIST30139:18145178827.3219.38668.33-1.01
CRISTOBALHUET1887:5386108836.8211.48677.79-0.96
DOMINIKHASEK18129:3494138616.0215.08406.96-0.94
JOSETHEODORE1570:085268845.137.098636.06-0.93
RICKDIPIETRO32195:02160188875.5320.88696.41-0.87
DANELLIS1470:055568905.136.958735.95-0.81
RYANMILLER31188:19163198836.0520.88726.62-0.57
PATRICKLALIME1059:234368606.066.528486.58-0.52
JOSHHARDING1570:0385108828.5610.68759.07-0.51
ANDREWRAYCROFT1046:524968777.686.398698.18-0.49
EMMANUELLEGACE23141:0785108824.2511.18694.73-0.48
VESATOSKALA29166:53143198676.8320.28587.27-0.44
TIMOTHY JR.THOMAS22105:52113138847.3613.78787.80-0.44
NIKLASBACKSTROM22129:46109148716.4714.48676.67-0.19
ROBERTOLUONGO29164:10161228638.0422.48608.21-0.17
JOHANHEDBERG2095:4491128687.5212.08677.54-0.02
OLAFKOLZIG28160:23168228698.2321.98698.220.003
J-SEBASTIENAUBIN1342:185378679.926.968689.870.056
RAYEMERY1259:405778777.036.878796.900.130
ALEXAULD1569:4078118589.4710.68639.140.327
DWAYNEROLOSON22106:40116178539.5615.98628.940.618
CAMWARD27146:32144228479.0019.98618.150.855
MARTINBIRON28156:17157218668.0618.78807.190.867
KARILEHTONEN1361:1672108619.799.058748.860.930
DANYSABOURIN1876:0776118558.679.798717.710.953
ILJABRYZGALOV25136:19118188477.9215.88666.950.963
CHRISMASON24114:0377118575.789.068824.761.020
JEAN-SEBASTIENGIGUERE27159:32156248469.0221.08647.921.101
MARC-ANDREFLEURY2198:20104168469.7613.58698.281.482
PETERBUDAJ2291:3886158259.8212.28578.001.813
MIIKKAKIPRUSOFF35204:31166298258.5021.38716.252.250
ANTERONIITTYMAKI835:5634779411.65.088508.483.205
JOHNGRAHAME1153:52521080711.16.718707.473.664

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Sunday, December 23, 2007

2007-08 5v5 Goaltender Performance

I've put together a simple first-order system to analyze goaltender performance. First, I calculated the probability of scoring from 2x2-foot quadrants using data from 2001 through last week's games:



I then took every shot faced by each goaltender and calculated the number of goals we'd expect an average goaltender to allow is he faced the exact same set of shots. [Note that shot distances are relative to the end boards, not to the goal line.] This is obviously a coarse estimate: we have no information on whether shots were defended or screened, and because of the difference in the way shot types are recorded in different arenas, I haven't differentiated between them. [Yes, in hopes of improving the system, I am happy to accept critical comments!]

At any rate, the table below shows the number of goals allowed by each NHL goaltender this season (minimum: 300 mins) and the expected number of goals allowed by an average goaltender.

So as an example, Henrik Lundqvist has allowed 41 goals on 567 shots at 5-on-5, for a 927 save percentage. However, an average goalie who faced the 567 shots from the same locations would expect to allow 58.3 goals, for an 897 save percentage. On a per-60-minute basis, Lundqvist's Goals-Against-Average is 1.90 - 0.80 goals lower than an average goalie. I'll publish some charts for individual goaltenders so we can compare the best goaltenders to the worst in this metric.

PLAYER STATSEXPECTED STATS
PLAYERGPTOISOGGASPCTGAAEXGAEXSPCTEGAADELTAGAA
TIMOTHY JR.THOMAS22977:05521239551.4144.69142.74-1.32
HENRIKLUNDQVIST311289:26567419271.9058.38972.71-0.80
CRISTOBALHUET18773:04411259391.9434.99152.70-0.76
ILJABRYZGALOV25924:13442259431.6236.49172.36-0.74
CHRISOSGOOD19797:26337229341.6531.79052.39-0.73
ROBERTOLUONGO291160:50536309441.5542.79202.20-0.65
MARTINGERBER24964:07542389292.3648.19112.99-0.62
JASONLABARBERA22889:57477379222.4944.39062.99-0.49
EMMANUELLEGACE23934:54394289281.7935.69092.28-0.48
CAREYPRICE17728:33386299242.3834.49102.83-0.44
MARTINBIRON281088:09615419332.2648.89202.69-0.43
JEAN-SEBASTIENGIGUERE271013:22433319281.8337.79122.23-0.39
CAMWARD271086:42530419222.2647.89092.64-0.37
RYANMILLER311254:29602459252.1551.99132.48-0.33
RICKDIPIETRO321283:57601469232.1452.49122.44-0.29
DANELLIS14502:01230169301.9118.29202.18-0.27
TOMASVOKOUN321346:02726549252.4059.79172.66-0.25
VESATOSKALA291168:59554479152.4152.09062.66-0.25
PASCALLECLAIRE23856:31374249351.6827.09271.89-0.21
NIKLASBACKSTROM22894:17394289281.8730.89212.07-0.19
MIKAELTELLQVIST10393:12199159242.2816.19182.46-0.17
ALEXAULD15620:41296229252.1223.79192.29-0.17
EVGENINABOKOV351446:58607469241.9049.69182.05-0.14
FREDRIKNORRENA15527:50237209152.2721.09112.39-0.12
MIIKKAKIPRUSOFF351438:23660549182.2556.89132.37-0.11
MARTINBRODEUR301286:11531449172.0546.49122.16-0.11
NIKOLAIKHABIBULIN25970:42421399072.4140.49032.49-0.08
PATRICKLALIME10390:04167159102.3015.49072.37-0.07
MARC-ANDREFLEURY21760:41388329172.5232.49162.55-0.03
KARILEHTONEN13472:40250229122.7922.29112.82-0.03
JOHNGRAHAME11435:36238229073.0322.29063.06-0.03
PETERBUDAJ22906:00419359162.3135.09162.32-0.00
MARTYTURCO251082:27473409152.2139.39162.170.037
JOSHHARDING15579:25313259202.5823.69242.450.138
DOMINIKHASEK18656:53207199081.7317.29161.570.160
MATHIEUGARON18686:55327319052.7028.79112.510.193
RAYEMERY12432:39176169092.2114.49182.000.217
CURTISSANFORD8316:27151139132.4611.79222.220.235
OLAFKOLZIG281175:33510528982.6547.29072.410.242
DANYSABOURIN18650:38316319012.8528.39102.610.248
DWAYNEROLOSON22852:05463429092.9538.49162.700.250
CHRISMASON24877:12434458963.0739.89082.720.350
BRENTJOHNSON9344:40165178962.9514.79102.570.386
MIKESMITH12465:48206228932.8318.99072.440.387
HANNUTOIVONEN10394:32195228873.3419.19012.900.436
JOHANHEDBERG20795:09419428993.1635.39152.660.499
JOSETHEODORE15618:30280348783.2926.49052.560.736
JOHANHOLMQVIST301190:12508588852.9243.29142.180.741
J-SEBASTIENAUBIN13427:15214248873.3717.99162.520.848
ANDREWRAYCROFT10344:49166198853.3013.59182.360.941

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