Examining Goalie Workload

If you listen to pre-game press conferences, there's one question you're likely to hear asked of a head coach: "Who is your starting goaltender?" While sometimes the answer may create follow-up questions from assembled media as to why a decision was made, there's one scenario that rarely does: when a team is playing back-to-back games.
In recent years, it has become an NHL standard. If your team is playing two games in two days, each of your rostered goaltenders is likely going to get a start.

The Kraken have played five back-to-backs this season and within each of those series-with at least nine more to go-head coach Dave Hakstol has divided the net between his two active netminders: "Typically you're going to have a split on the back-to-backs."
But why is this?
Our gut tells us it makes sense to take advantage of playing a fully rested goalie after the other has played a full 60 minutes, but are there more concrete reasons that support this overall strategy? After all, we see skaters play night after night. How tired might a goaltender actually be if they play two consecutive days and how much does it affect performance?
Let's dig in.
Across an NHL regular season as a whole, the usage of the two players that make up a team's goaltending tandem has changed over the years. Go back a few decades and teams clearly deployed the "A Starter," who played the vast majority of games (as much as 70 percent and a select few starts even more) while a backup was looked to much more rarely and entered games sparingly.
That workload split was narrowing only slightly when, in 2013, Eric Tulsky, (now assistant general manager with the Carolina Hurricanes) looked into the effects on save percentage of a goaltender playing in both nights of a back-to-back. He found that playing a goaltender two days in a row reduced their save percentage by just over 11 percent.

To put that in perspective, if we look at the 1,019 NHL games that have been played this season (through Jan. 2), on average, a goaltender sees 31.5 shots on goal and saves 28.4 of them. Reduce that ability by 11 percent and you're closing in on three more goals against per game. That's pretty significant!
Since Tulsky's study was released, we've seen a precipitous drop in the same goaltender playing back-to-backs. And while follow-up studies by SportsMEDIA Technology's (SMT's) Andrew Thomas and The Athletic's Dom Luszczyszyn have shown the impact on save percentage may not be as significant, splitting the net in back-to-back games has become the standard we know today.
Other big-picture factors have played into the idea of managing goaltender workload.
Just as teams now address the fatigue incurred by playing two games in a row in net, they also look at the cumulative effects of total playing time (much like we see in the NBA or NFL) across a season.
Preserving your top players for long-term performance (including playoff series) is a factor in the amount of games coaches might assign to their top goaltender.
Similarly, organizations have become increasingly comfortable with building true goaltending tandems with a "1A" and "1B" goaltender (when the difference in ability is not massive) as opposed to a "starter" and "backup."
This type of roster construction gives teams much more flexibility in their deployment and, if we go back to the back-to-back scenario, if the difference in save percentage between your two netminders is less than an anticipated drop in performance in a "two games in two nights" situation, it makes sense to alternate goalies rather than suffer if the same player goes into the net two nights in a row.
Don't be surprised when you see any team use both of their goaltenders when playing back-to-backs. The order of which goaltender goes first may change-it can depend on the opponent or the number of days of rest since one last played. But splitting the net is an NHL trend that, at least for now, is here to stay.
Data via NaturalStatTrick.com; represents all situations