Clearing up some questions about scoring chances
By Cam Charron
10 years agoat the 36 game mark, the Leafs did actually out-chance their opponents 474-469. Edit: I erred on my interpretation of these numbers — the original included special teams. The actual numbers available to us are 392 against and 355 for on even-strength. However, this isn’t the chasm inferred via shots total against. But it does leave me wondering what Cam’s final scoring chance counter was.The Leafs out-chancing the opposition doesn’t necessarily mean anything. But it does give credence that the coaching staff actually knows what they want out of their line-up, how to get it, and what they are tracking. Oddly enough, the narrative that Carlyle and Co. don’t have a clue what they are doing come from the lowest denominator of an internet arm-chair general manager from that other place.
It’s wonderful that people are using my data, I guess. Since the Greg Cronin interview came out last week, a lot of people have asked me if I have a final tally for the Leafs scoring chances numbers for and against on the season. They came out well-below even at even strength, having a brutal final 12 games of the season in chances. I don’t have an exact number because the other computer is in the other room and there’s some element of laziness because I’m trying to vacation and stay away from hockey for a week. I can’t quit you guys, but the 36-game update is all we have for some time.
For those not in the know, every Leafs game this year except for two, I sat in front of my TV and noted scoring chances. It’s a simple process. After the game, I go to NHL.com, check to see who was on the ice for each chance, and have a table at the bottom of games that gives each player’s “plus” and “minus”. It’s a good way to get people interested in analytics that’s more accessible than shot statistics.
Other than the fact that they could be score effects-neutral compared to shot statistics, there’s really not much value in these numbers. While it may be counter-intuitive, there’s no current evidence to suggest that players affect the save percentages of their goaltender. It is true that certain players allow a disproportionate number of shots in the slot or odd-man rushes when they’re on the ice, but that doesn’t mean that it’s sustainable. As Eric. T put it on NHLNumbers when this was a debate last summer, “Whatever tendency certain players might have for driving their team to get more scoring chances than a simple shot differential predicts is small and swamped by random noise”. If you want to draw any conclusions from my scoring chances data, make sure you read that post first.
Phil Kessel may take 20 shots, but only 5 of them are scoring chances, compared to, say, Nik Kulemin, who takes 10 shots but 4 of them are scoring chances. If you extrapolated the data, you would infer that Kulemin takes better shots than Kessel, but over the long run, they’ll probably even out to a cleaner percentage. Kessel also scores on a lot of shots that wouldn’t be considered scoring chances by the strict definition published at the Copper and Blue as do a lot of other players. I’d say about 25% of goals scored by both the Maple Leafs and their opponents this past season would come on plays that I didn’t mark down as a scoring chance. While some people love talking about “quality” shots when other people talk about Corsi statistics, you’d be surprised at just how many times a goal is scored not off an odd-man rush, a puck in the slot, or a rebound.
Don’t get fooled by noise, and don’t make conclusions about the Leafs’ appearing to have a higher rate of shots turning into scoring chances than their opponents last season. If you look at the 36-game update, you’ll find that a lot of players that perform well in scoring chances also perform well in Corsi, the table at the bottom of the post. Since there are much, much more Corsi events than scoring chances in a given game, I much prefer looking at those. Scoring chances are rarer, and I’m not fully convinced that there’s any good practical application of the data at this point.
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