A lot of the time gut feel works just fine in assessing a player, and a guy's ability to finish is a big part of that. There is no doubt that Heatley
has more finish than Dvorak, the memories of Dany's
highlight reel goals and Dvorak's blown chances as an Oiler
... these colour our opinions, and their history of shooting percentage confirms them.
Now playing on the powerplay
helps a guy's shooting percentage a lot, especially if he is the trigger man
and if he gets a lot of 5 on 3 powerplay
time as well. Getting a few empty net goals really helps this number as well. So here we'll just look at even strength goals that happened with both team's goalies on the ice (EVshooting
Now everyone knows that even the league's premier goal scorers will have cold stretches this season, almost all of them will have a month (20 to 30 EV shots) with a brutal EVshooting
%. And while some fans will get excited about it and start searching for reasons, most will accept that it's just the Hockey Gods in action. If Iginla
has a stretch of five weeks with just one EV goal (say 1 goal on 30 shots, 3.3% EVshooting
%) most around here will chalk it up to random chance. And they're probably right. mc79hockey.com
has shown that the pattern of EV shooting% is very nearly identical to that expected by chance alone, granted only four players were studied. Still, it's impressive considering that line mates
, injuries and psychological elements are surely factors. So while those things are likely all in play, they are extremely difficult to detect through the noise of luck. Plus I've never read or met anyone who has been able to predict future shooting% trends.
So we're good at sensing the level of luck involved with the small samples, where the human mind let's us down is over a larger number of games and shots. It feels like a season, or certainly two seasons, should be enough to give us a good gauge of a player's true finishing ability at even strength NHL hockey. My own gut feel would be "within one or two percent" after two seasons, and I would be wrong. And going by the things I read on the internet
, I suspect that most people would mentally put a narrower error band on it than me.
Below is the confidence interval for a mythical player who we know to have a natural 10% EVshooting
% ability. If Tyler is right, or largely right, then this is the range of results that we should expect to see from the player 95% of the time. And if we looked at 100 identical players, after any given interval 5 of them would be outside this range of shooting%.
A top six player will probably get about 130 EV shots in a season. Less than that if he is playing on a weak team, more than that if he is playing on a territorially dominant team. And a 10% EVshooting
% ability is about what you'd expect from a top-six-ice-time type of forward. You'd want more than that if the player brought little else to the table, and could live with less than that if he had a wider range of skills. But that's a reasonable midpoint.
So the chart above reflects a total of about four seasons on a good team, and about five seasons on a weak team.
After 60 even strength shots, about half a season, our man's 95% confidence interval ranges from 2.2% to 17.4%. That's a hell of a swing. That means that in 100 parallel universes, our man would be expected to have an EVshooting
% in that range 95 times. And the universe requires him to be higher or lower than this 5 times on average. It's cruel in a way, if our man doesn't have a track record in the NHL, then some of the parallel universe versions are being rewarded with rich NHL contracts, while in other parallel universes our man is being buried in the minors or shuttled off to Europe. All at the caprice of the hockey gods.Speeds has an excellent post up
on the most recent Oiler
first round draft pick. Every scout seems to have seen him good, but the offensive numbers aren't where we would want them to be, it appears that he hasn't scored enough to justify the draft position. Speeds points out that he had a poor shooting%, and wisely suggests that it could be either because he doesn't have much finishing ability or that he was simply unlucky. And that we have no way of knowing which is true until time reveals more information.
And even for a guy like Cogliano
, who has shot the lights out so far, he has only fired about 200 EV shots thus far in his career. So all we really know is that he is very likely (about 95% likely) to have a true EVshooting
% within 5% of his rate so far.
So how good is Cogliano at finishing his chances? The skeptics and determinists can send their poets out to battle each other all day and night, but the fact of the matter is that we just don't know. We do know something close to the true probabilities, but it's still such a wide band that very few people would be foolish enough to bet the rent on him maintaining his current level.
The same intervals apply to on-ice EVshooting
% for all players as well, though the larger sample (i.e. number of EVshots
) is typically about four times higher. The same also applies to goalies and EV save percentage of course. So while we are judging goalies largely by EVsave
%, which is sensible, we always have to remember just how volatile these can be in the short term. And while we can predict the behavior of the population, we can't predict which ones will throw more than their expected number of bullseyes
This summer, teams that paid for players based on results that came from a year or two of good percentages ... they'll most likely regret it. Teams that have paid for players with good track records but a recent stretch of poor percentages, those were probably good bets.