What advanced stats say about NHL outdoor game scoring chances

Matt Pfeffer
Yankee Stadium

NHL outdoor hockey is here to stay. Before the Rangers-Islanders game at Yankee Stadium, I broke down the data to see if there was anything advanced stats could tell us about how playing outdoors has affected the games. Although we only have nine games to work with (the 2003 Heritage Classic in Edmonton was played before the RTSS era), there have been some noticeable effects on the way those games have been played. I’m going to focus on shooting, because that seems to be a place where we can see a discernable difference between indoor and outdoor.

Shooting percentages at even strength have been dramatically reduced on outdoor ice. The average even strength shooting percentage indoors since 2007 has been 8.2 percent, while the nine outdoor games played over the same time period has been 6.8 percent. To give you an idea of how drastic a difference this is, the worst shooting team in the league since 2007 has been the New Jersey Devils: they have an even strength shooting percentage of 7.2 percent. Teams playing outdoors have had worse shooting success than any team in the NHL playing indoors.

An obvious place to start when trying to figure out the reason for this drop is the condition of the ice. There will be more snow on the ground when playing outdoors. This can cause a larger amount of resistance on the stick when attempting a shot. But teams also seem to be intentionally changing their shooting patterns, too. The average shot attempt in a normal NHL game comes from 36.3 feet out. Average shot attempts in outdoor games have come from 38.8 feet from the net. Two and a half feet may not sound like much, but we know the chance of scoring is reduced the farther from the net you shoot. And of course, the farther out you shoot, the more prone you are to miss the net or have your shot blocked. But the data from outdoor games tells us this hasn’t been the case.

outdoorgraph

In fact, although outdoor shots have come from farther out than they usually do in NHL play, the percentage of shots that are blocked is 4.03 percent lower. Tip-in shot prevalence is also reduced by 2 percent outdoors, suggesting forwards are less willing to put themselves in the line of fire outside. Hockey players are tough, but they seem to get less tough in the cold.

Outdoors, teams seem to be taking chances from farther out and they’ve paid for this with lower shooting percentages. Goaltenders, rather surprisingly, have had an easier time outdoors than in normal NHL play. With less physicality and fewer bodies in front of the net, teams playing outdoors might benefit from working harder to get the puck in better scoring locations before they shoot.

Coaches have tried to test the goaltenders more on outdoor ice, but they haven’t gotten much out of it.