A challenging task

While the page "Coaches - Challenges" has been present on my website for a long while, it was always bothering me with a variety of inaccuracies, as well as the inability to properly incorporate another event, when the Situation Room interferes with the game: the Video Review. Therefore I put myself to a task of comprehensive accounting of all Coach Challenges and Video Reviews dating back to 2015.

The main information about challenges and reviews comes from the Play By Play sheets. In many cases the flow is straightforward:

• There's a CHL event with the type of challenge and the challenging side
• There's the outcome in form of the timeout event by the challenging side

Unfortunately, the data is not very consistent and in many cases, lacking. Sometimes there's no CHL event, but instead a STOP event with a CHLG string. Sometimes the timeout is not there. Sometimes the challenge is attributed to 'League' - something that should only happen in the last minutes of the third period or in the overtimes. Sometimes there are two challenges, and one is missing. And sometimes even the wrong team is attributed to the challenge. While overall the NHL data is pretty steady, the challenge is the worst - probably because it involves a lot of human-contemplated input. And a lot of Video Reviews just go AWOL from that event sheet.

Fortunately, from about mid-2015 season, NHL publishes the "Situation Room Blog" - a rubrique on its site that is very scrape-able and moderately structured. Thus I was able to pick all the Situation Room proceedings since around January 2015 and parse them into a structure similar to the challenges from the PBP sheets. Then I was able to cross-compare the lists per game. That allowed me to correct quite a few challenges as well as add more challenges and video reviews.

The total tally includes:

• 885 Coach challenges from CHL events
• 264 Coach challenges from STOP events
• 30 Coach challenges from Situation Room blog
• 56 Video Reviews from CHL events
• 937 Video Reviews from STOP events
• 216 Video Reviews from Situation Room blog

Altogether 2388 events.

I consider the League Challenges equivalent to Video Reviews.

In the next blog post I'll show how they are breaking down by outcomes for each team and in other ways. I plan to add a page of challenges and reviews in the Team section of my website.