Shift Ends and Shot Rates

Yesterday, Tyler Dellow had an interesting post over at The Athletic (paywall) examining why not all ice-time against opponents is created equally. By drilling down on how the Leafs’ defensive units fared against various levels of competition last year, Tyler was able to dig into why Toronto’s bottom pair was able to do better against top 6 competition than their top pairing did.

The whole thing is a worthwhile read, but the one line that stood out to me was this:

The point is that [Roman Polak and Andreas Borgman] got time against the opposition’s top line in circumstances in which that line didn’t really pose an attacking threat.

The overall idea that Tyler presented is pretty intuitive but also incredibly important: if you come on the ice when your opponent is finishing their shift, they’re unlikely to be mounting much of an offensive push, and most of their effort will likely be focused on advancing the puck out of their zone and getting of the ice.

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Posted in Zone Starts

Optimal Contract Structuring: “Taking It To The Logical Conclusion”

Last February I was fortunate enough to attend the Sloan Sports Analytics Conference (mostly due to the excellent work of the ever-amazing Ryan Stimson). One of the marquee events was a panel titled “Moneymind: Overcoming Cognitive Bias“, which featured 4 of the best known “Money[sport]” GMs (Daryl Morey, Sam Hinkie, Farhan Zaidi, and Billy Beane) talking about how they make decisions and what makes their  respective management styles different from most executives in their sports.

While the whole panel was endlessly informative and extremely entertaining, one thing Daryl Morey said about the Rockets approach to implementing strategies really stuck with me:

“One thing I think all of us have done is more take the lessons that are sort of obvious that everyone has agreed to and taken them to the logical conclusion. Which is, for example us, it’s better to make 3 than 2 on a shot…genius, right…taking it to it’s logical conclusion, which is shoot 50 of them a night.”

Basically what Morey was saying is that if all the work you’ve done has shown that a strategy is beneficial, don’t hedge your bets and only go half-in on it. It’s this idea that’s been floating around in my head for the last 2 days since I wrote about optimizing contract structure – if GMs could theoretically save cap space by setting up contracts to pay more money to players upfront, how much total cap room could they create simply by structuring their contracts in the most efficient way possible?

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Posted in Salary Cap

The Time Value of Money and Player Valuation

One of the weird but infrequently mentioned quirks of salary negotiations in the NHL is the competing interests of players and owners with regards to how the actual salary payments should be structured. While analysts tend to focus on the AAV when evaluating a deal, the details of how much a player gets in each year are actually critical to understanding how much a team values a player.

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Posted in Salary Cap

Game Theory and Defending Against a 2-on-1

Last night, Jake Gardiner made a bad decision. Faced with a 2-on-1 in a tie game midway through the 2nd period, Gardiner made what seemed like the smart choice – he played the pass, leaving Curtis McElhinney to deal with what appeared to be an easy foe in 34-year old Trevor Daley[1]. Daley, however, defied the odds[2] and placed a perfect shot in the top left corner to give the Red Wings a 2-1 lead.

While defensemen are often taught to take the pass and leave the shooter to the goalie, Gardiner’s execution left a lot to be desired. As Justin Bourne noted, when you give the shooter that much space you’re basically turning a 2-on-1 into a 1-on-0.

Beyond the poor execution though, there’s a more general question about the wisdom of playing the pass and not the shot. Taking the pass and trusting your goalie to stop the shot is an idea that’s drilled into defencemen’s minds from a young age, and on its face it makes a lot of sense – we know that shots of passes go in more often than those off shots, so if you’re looking to minimize goals against (a pretty good idea for a defencemen) your best bet is to take away the higher percentage play.

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Posted in Game Theory

Quick Thoughts: 4-Forward Power Plays and Protecting A Lead

The other day I tweeted out a bunch of stuff about why teams may want to avoid a 4-forward power play when they’re up late. I’m not going to bother turning this into a full post, but I’ve linked the tweets here so they’re actually saved in a (somewhat) organized fashion).

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Posted in Powerplay

How certain do you need to be on an offside challenge?

Offside challenges are, to say the least, a controversial topic. While many have advocated for the benefit of getting the call right even at the cost of a delay in the game, it’s almost indisputable that the introduction of the offside challenge has slowed down the flow of the game. Over the past two years, coaches have challenged any play that was remotely close with the hopes of getting lucky on the video review, to the dismay of basically anyone other than replay technicians.

Those spurious challenges are one reason why the NHL modified the rules around coach’s challenges yesterday. Starting next season, instead of a failed challenge simply resulting in the loss of a team’s timeout, clubs will now face a 2 minute penalty for losing an offside challenge. Upon hearing of this change many fans were apoplectic, complaining that this rule change could bury teams who were already reeling from giving up a goal against, and would severely limit the willingness of coaches to challenge even legitimate missed offside calls.

Fan reaction notwithstanding, however, the question coaches should be asking is whether they should be changing their approach in response to the new rules. The threat of killing off a penalty for a failed challenge may seem like a big deal, but it’s important to note that teams only score on roughly 20% of their power play opportunities. Fans will surely remember when a failed challenge leads to a power play goal against, but there will certainly be occasions when the potential gain from overturning your opponent’s goal outweighs the risk.

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Posted in Theoretical

Should teams play with 4 forwards when they’re down late?

Embed from Getty Images

This post originally appeared on Hockey Graphs.


  • There is some evidence to suggest that teams should play with 4 forwards when trailing late in a game.
  • The timing of when to switch to 4 forwards is dependent on how large an impact the switch has on goal scoring rates, however even with a low impact on goal scoring, using 4 forwards still makes sense.

One of the weird things about sports that I find fascinating is how often coaches and players seem to go out of their way to avoid having a negative impact on the game, even at the expense of potential positive impacts. People often seem to prefer to “not lose” rather than to win, which can result in sub-optimal decision making, even in the presence of evidence to show that the correct decision is not being made.

There are many examples of this across sports, but the biggest two in hockey are pulling the goalie and playing with 3 forwards on the power play. Analysts have been arguing for many years now about why teams should pull their goalies earlier, but it’s only been in recent seasons that teams have become more aggressive in getting their netminders out earlier.

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Posted in Theoretical