Tuesday, June 30, 2009

The General Idea

The Y-axis is Corsi differential (shots directed at net) at 5V5 for 2008/2009.

The X-axis is Shifts Ending with Faceoffs by Zone (Offensive - Defensive) at 5V5 for 2008/2009.

The blue dots are the Oilers skaters.

The red dots are the Flames skaters.

I think we can see the problem here.

Wednesday, June 24, 2009

Keeping Your Powder Dry

There are basically two ways to build a Stanley Cup contender and it doesn't seem that the Oilers have been following either approach:

1) Suck for a pretty long time. Three years is a good start, but you might need an extra year or two depending on your drafting record.


2) Build a reasonably cheap team and collect some prospects and picks in the event that an elite player in his prime hits the market. Joe Thornton and Chris Pronger come to mind as examples and there have certainly been others.

I recall Tyler Dellow used the title phrase to describe this latter strategy back when the Oilogosphere was mostly on the messageboards and I think it's a good way to think about it. Plus with Pat Quinn as the new head coach old-timey phrases are de rigueur. (Although he might not approve of a saying that originated with Cromwell.)

Skip forward a few years and #2 seems a lot more like an actual plan than it did before. Thanks to the salary cap and more liberal free agency in the current CBA, it seems almost commonplace that elite-level players with years of prime production come available every offseason. However, you still have to keep your powder dry to take advantage and that happens to be the Oilers' problem.

Just the public list of available talent is tempting and we don't even know who teams like Boston are willing to move to open up cap room.

- The Sedins hit free agency and they're still only 28. The only catch is that you probably have to take them both.

- Bouwmeester is truly an one of a kind free agent as mentioned by speeds over at his site. A legitimate #1 dman at the age of 25 available as free agent? Bonkers.
- Gaborik, Hossa and Havlat are all players with proven track records for driving results and should each be able to provide 4-5 years of quality production. The catch is that you probably have to sign them for 2-3 years beyond their best before date and Gaborik and Havlat have serious injury concerns.
- Lastly, there's Dany Heatley. He's an interesting player, mostly because the Oilers haven't had a player quite like him in a very long time and I'm not even sure what his value would really be, because he's not like the other players I've already listed.

Let's take a look at some of Heatley's selected stats:

The first thing to note is that he's obviously an accurate shooter. Four straight years since the lockout with overall SH% greater than 15%. That is impressive. The second interesting thing is that he has seen his PP icetime drop as a percentage of his total icetime over these four seasons. That doesn't necessarily mean anything but it probably explains why his shooting rate appears to be declining over that same period.

If you check out Vic's timeonice.com site, you can find the underlying stats for Heatley for the past two seasons.

The Corsi is good, but you'd expect that given the starting position of his shifts.
What jumps out at me is the differential in faceoffs starting and ending shifts. I would expect a coach to use a player like Heatley this way, but I'm a little shocked so many shifts ended in his own end. I haven't looked at this before, but is this typical for a serious offensive player like this? At 5v5 Heatley is still shooting the lights out and I'm guessing he's a pretty consistent 13-16% shooter at ES, which is again impressive. However, given the underlying numbers, it's probably safe to assume that Heatley has seen his regular season production as an NHL player driven by favourable starting position and high shooting percentages (and of course some pretty decent linemates). I don't think that's really what the Oilers need right now. They need more players that move the puck to the good end first. The problem with a player like Heatley (besides the fact that they're really really expensive) is that your team has to be pretty good already to make use of him. The Oilers aren't there yet in my opinion, so at least with Heatley maybe it's a good the powder is long gone.

As for the rest of the offseason, I'm hoping for a couple of players that drive possession, but I honestly don't know how Tambellini is going to make anything happen. Adding any one player of quality (that is paid commensurate with his ability) is going to require a minimum of 2-3 deals and that's a hard thing to count on. Two players is probably a pipe dream.

Monday, June 08, 2009

Real Effects and Team Shooting Percentage at Even Strength

'Real Effects' is a term I'm stealing from Bayesian mathematicians. The idea is that if an element of nature is affected by something other than randomness, that it should sustain itself from one independent sample to another.

So if we look at MLB baseball players and their ability to hit home runs, as a percentage of balls that they put in play ... well the Real Effect is enormous. There is a strong association from one set 50 of random baseball games in a season to 50 other random games from the same season. Using Pearson correlation as a convenient way of measuring that relationship, it's around 0.9.

Of course randomness still has it's say, but it's a starting point, and tells that it is possible to separate the ability distribution from the luck distribution for this element of nature. There are no Real Effects for 'players who hit better on natural grass', or 'RH batter vs LH or RH pitcher' (obviously players do a lot better against opposite hand pitchers, just that there is no evidence to suggest that, in the general population, some guys do it better than others). For that matter there is no real effect for the majority of the stats recorded at baseball-reference.com. Though surprisingly there is for most measures of clutchness in baseball.

In this case team I'm looking at Team EV Shooting% for the 08/09 season. Inspired by Jlikens terrific work on the subject over the past season.

Jlikens looked at the distribution of EVshooting% for the 08/09 season, this versus what we would expect the random distribution to look like, and found that there was very little in it. That the overwhelming majority of differences between teams EVshooting%'s was accounted for by luck alone. Surprising stuff, even for the cold hearted folks around this part of the internet.

Of course with just 30 teams in play, it's possible that this distribution occurred by chance. It's like if we were assessing the fairness of a coin flipping contest, where we knew that the coins were weighted differently. If we just looked at one 'season' of coin flipping, it is possible that by chance alone, the spread of results would appear to be the same as that of fair coins. Just because a few of the guys with good coins happened to have a spot of bad luck flipping, and the opposite for some of the guys with poor coins.

So, I thought I would check for real effects with team EVshooting% by upping the sample sizes. For the 08/09 season I randomly selected 19 home games and 19 road games. Then I just took the shooting% for when the score was tied and both goalies were in their nets, this to eliminate the goals from blowout games.

Then, of the remaining 22 home games I randomly selected 19 of them and did the same as above, grabbed the EV goals and EV shots from the tied-game state. Same for the remaining road games.

Then I checked for real effects using Pearson correlation.

Then I did the same thing 1000 times.

And while I was at it I also looked for the real effects of shot ratios and EVsave% while the score was tied.

The script that does it is here, and it will take about a minute to run. And every time it will use different random selections of games, each of these will be listed in the second table, but 1000 samples seems to be enough that the averaged result always ends up about the same:

Real Effects:

EVshooting%: 0.00
EVsave%: 0.14
SF/SA: 0.68

Jlikens is right. Damn, woulda thunk it?

I doubt that this is the case for the NHL in previous eras, especially the 1980s and around 2000. And clearly some players have a better ability to finish, though as MC79hockey has shown us repeatedly usually similar reasoning, that's much smaller than most of us realized intuitively.

And surely this will be the same next season. In fact if we decide right now who are the five best EV goalies in the league, based on EVsave% over the past few years, and eliminate them from next year's test ... then I suspect that we'll see the real effects for goaltending EVsave% fall to almost zero as well. Again, I don't think this was the case 20 years ago, but there are an awful lot of good goalies in the NHL now, and precious few real difference makers in that position.

In conclusion:
1. Possession may not be everything, but in the big picture it's damn close toit. The Oilers need players who drive the terriorial advantage. It would help if Pisani regained his old form as well, there was a time when the play just never seemed to die with the guy. And the forwards that the Oilers do have, they need to be willing to play more below the other team's goal line and finish their shifts more responsibly as well.
2. Unless you're getting an established star goalie, it doesn't make a lot of sense to spend a lot on a second tier guy, either in cap space or trade assets. Because the gap between 2nd tier and third tier appears tiny.
3. Guys coming off of poor percentage years, but with good underlying numbers, and who play a solid game ... these should come at reasonable rates. They should be players that the Oilers buy, not sell. (SEE Reasoner, Stoll and Torres from last summer).