Analytics with Alison: Controlling Second Periods

The Seattle Kraken continue to sharpen the details of their game, but some things have been working well for them-and that is winning second periods.
The middle 20 minutes of any hockey game present unique challenges. With goaltenders changing ends of the ice to defend every period, in period No. 2, whether you're a defender or an attacker, you must skate farther to get to your zone of responsibility (and you spend more time and energy to get off the ice, allowing for a shift change that brings on reinforcements in your stead).
The "long change" means you may have to sacrifice precious seconds of play to get back to your bench, or risk getting caught on the ice longer than is ideal. But the Kraken have been working around that challenge.
How? Let's dig in.

"(The second) is a possession period, for sure," Kraken head coach Dave Hakstol said a few weeks ago. "And we've been pretty good in second periods."
Hakstol isn't wrong. In the second period (using data from NaturalStatTrick.com), Seattle has earned the edge in 5-on-5 shot volume and quality in all but three of its 15 games. In eight contests, the second period has been the team's strongest of the game in terms of generating shots overall and it's been the best in terms of creating shot quality six times.
As a result, the Kraken outscored opponents 15-14 in second period play entering Saturday's game.
So, how is Seattle doing this? No coaching staff is going to give away all its secrets, but we know it in part ties to zone starts and replacing players with fresh legs while the team has possession in the offensive zone.
"It's definitely in our head (to) just make sure you're changing when you're supposed to," Kraken forward Ryan Donato said. "It is a big thing…changing in the (offensive) zone. Sometimes guys get tired and they don't have a choice but to change on the backcheck or change in situations when they really shouldn't. I think any time we have quick changes in the O-zone, it leads to good things and that's our recipe for success."
Are the Kraken truly shifting the degree to which they change out players in the offensive zone to combat the long change? Thanks to Sportlogiq, we can answer that question. Below is shift change data from Kraken games compared to overall league averages. This shows us the percentage of times teams are changing on the fly in each of the three different zones of the ice.

We see that while the Kraken hold true to league averages in terms of defensive zone and neutral zone changes, they're exceeding the norm when it comes to changing in the offensive zone.
Does this appear to translate to shifts that start on a faceoff, as well? Let's take a look.

Now, we see where zone starts off the faceoff are not happening as regularly as league average: in the defensive zone. So, yes, the Kraken have found a strategy that gets their freshest legs on the ice when they are in position to attack.
Are there any players who do this more than others? Well, we can look at that, too. The table below shows the difference between every Kraken skater's zone start percentage as compared to league average. So the bigger the number, the more a skater is changing in that zone as compared to the norm (these values are highlighted in blue).

It's neat to see just how many Kraken players seem to be changing exactly how their coaches want them to. As noted above, this is giving the team an advantage in possession in the offensive zone.
Remember: this isn't an all-encompassing look at what's helping the Kraken control second periods. There's plenty more we can investigate. This also isn't verdict on any player's value just because of where they are (or are not) changing out on the ice. Each skater has different skills and roles that may or may not have them focused on, or having the opportunity to, perform the changes we're talking about here.
But overall, the Kraken are doing what Hakstol has designed, and that's important because as he said: "starting with the puck . . has a way of generating momentum, especially in the second period."