Tuesday, January 15, 2008

More Save Percentage than Save Percentage

While the rest of you suckers will have to sit through Rob Brown's "analysis"—I used to think that his problem was that he was used to radio, where you had to explain everything in detail to people who couldn't actually see the play, but after watching the first half of Sunday's game before being forced onto the CHED broadcast, I realized that while the rest of us are watching and quite possibly thinking about hockey, Rob Brown is actually surfing YouTube for videos of funny cats, because any time he's asked to provide even the slightest bit of enlightenment on the game he's ostensibly spent the majority of his life around, he provides a level of commentary so banal and mindless ("The Oilers are going to need to hold on to this lead, Morley") it could only come from the mind of someone who has just spent the previous 10 minutes chuckling at a tabby chasing a laser pointer to the tune of "Yakkity Sax"—I will actually be at this game in person with my exceedingly generous younger brother, getting drunk off $7.50 beer and inadvertently teaching 9-year-olds creative ways to swear at Ladislav Smid.

In any event, the fact LA is in town dovetails nicely with the recent announcement that Mathieu Garon has taken over the starting role from Roloson, and has got me thinking: I was all set to write something ripping the Kings for letting such an obviously talented goaltender go, but looking over Garon's stats, there's really not a whole lot before this year to suggest that Garon was anything better than a capable backup. His two seasons in LA saw him drop save percentages of .894 in 63 games and .907 in 32 (though he did post a .918 from Jan 1 on last year).

Which brings me to another point: though I think save percentage is pretty much the best stat we currently have to judge a goaltender, it's pretty far from perfect. One of the things I think that's grossly undervalued in the stat is shot quality: obviously, a goalie facing a steady diet of breakaways and back-door plays is probably going to save a lot fewer pucks than one facing shots from the side boards, whether he's Roberto Luongo or Dan Cloutier. I think, though, I might have some kind of solution, not that I can actually go about implementing it (stat guys: hint, hint).

Desjardins' has recently started putting together shot charts that look at shooting percentage by zone. If it's at all possible to put that together for individual goaltenders, I think we could begin to look at what a goaltenders expected save percentage might be. I'm sure this is way more complicated than I'm about to make it seem—I'm more comfortable around thesauri and fermented liquids than math—but if you basically just add up the expected save percentage from each zone (properly weighted to reflect actual shot totals and the situations—5v5, PP, etc—those shots came in, of course), you'd get a number reflecting what the average goalie's save percentage would be, had he faced those shots. Then, you just compare the goaltender's actual save percentage to his expected, and voila: you have a number that minimizes shot quality, and by extension things like team performance.

I would expect that we wouldn't learn a whole lot about the top and bottom tier goaltenders (though it would give insight into something like just how much Brodeur was helped, if at all, by the Devils defensive system, for instance), and a lot of what we learn would probably seem fairly apparent—Pascal Leclaire's SV% is probably being helped mightily by Hitchcock's system, for example—but I think it could shed a lot of light on the middle-of-the-pack guys like Monsieur Garon, and in any case it's always better to go off stats than anecdotes and conjecture.

Anyway, someone tell someone to do this: I have drinking to do. GOILERS.


Bill said...

I still think Garon's nickname should be Gumby.

As for the statistical analysis of goalies based on angles and shooting areas and soil conditions ... Holy shit! If he stops pucks he's good. If he doesn't, he sucks. I don't have time for spreadsheets.

(Yes, I know other factors are involved but let some other geek waste his time figuring that crap out. I've got beer and wine that need attending to.)

Devin said...

That marvelous bastard called Javageek does something like this (adjusting SV% to a shot-quality-neutral standard). http://hockeystats.no-ip.org:81/goalies.php?id=2

Kirk said...

Maybe this is old news but Rogers has a free centre ice promo right now so any digital customer is able to get this game.

I'm watching for free right now in T.O. on ch. 457.

Cheers! GOILERS!


mike w said...

Motherfucking Rob Brown. His colour man M.O.: 1) re-describing plays that we all just saw 2) repeating things that other people say.

Here's a paraphrased example:

Ethan Moreau: "Well that's unacceptable, we have to play better in the second period."

Later, Rob Brown: "Well they're clearly not going to be happy with that period and will have to play better in the second period."

Thanks for the insight, Bub.

Perhaps in the 2nd he'll go on about how the Oilers will "need a really strong shift here" for 36578th time? We'll see.


Dennis said...

Kirk, all the dish and cable companies had the same promotion; it was from last wed tonight and ends tonight. Pretty fortunate for me because I had some renovations going on at the homestead and I stayed at my sister's place for the week and they have digi cable but now CI. But because of the preview I got to see last Thurs and Sun's games on their big screen. Neither was avaiable in HD though.

MikeW: Brown is such a gigantic dummy. He's got that permanent smile along with those hairplugs that somehow never came in and it makes me angry to look at him;)

Andy Grabia said...

Poor Dave, he'll never get the 2.5 hours of his life back. I left the BPs after the second Kings goal. Just awful fucking hockey.

My favorite Rob Brown moment: 1st period, Oilers down 1-0, and they take a bad penalty. Brown says, and I quote, "the Oilers have a great opportunity to get some momentum back by killing this penalty." Agreed, Rob. Whenever my team is down a goal, and are playing poorly, I look for them to go shorthanded for two minutes. Makes them bare down and focus.

mike w said...

Yep. It's an ass of a game.

mike from ottawa said...

It was entertaining to me to see Oilers wingers try to defy the laws of physics on more than one occasion, namely by attempting to squeeze their bodies through a six-inch gap between the boards and a Kings defender in the neutral zone, and then look on in bewilderment after they give the puck up on an odd-man rush.

Kyle Brodziak, I'm looking in YOUR direction.

MetroGnome said...

We'll trade you Charlie Simmer for Rob Brown. It's one of those trades that's fairly equitable in that both sides lose.

garnet said...

We're losing 4-1 to the 'Canes? Are we gonna get swept in a Southeast road swing? Sigh.

garnet said...

7-2 final. I can see why we're only talking about the Oilers in abstract statistical terms now.