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Learning the game: What is Shot % and why should you care?

A study on William Karlsson and the consistency of shooting percentage.

Winnipeg Jets v Vegas Golden Knights - Game Three Photo by Isaac Brekken/Getty Images

The hockey statistics world has become a completely new animal in recent years. Gone are the days when fans look simply at goal and point totals. To really understand how good players are, we need to start looking deeper into how and why certain players put up the numbers they did. Today I’d just going to scratch the surface of the available data and talk about shooting percentage. Shooting percentage is a pretty self-explanatory statistic: it’s the percentage of a player’s (or team’s) shots on goal that find the back of the net. In equation form, it’s shown as
S% = (Goals/SOG) x 100%

Enter “Wild Bill”

The Golden Knights were arguably the best storyline of the 2017-18 season. They garnered attention not only in the hockey world, but from sports fans who never followed hockey before as well. One of the best storylines within this storyline (storyline-ception, if you will) was the emergence of William Karlsson. To call last year a “breakout season” for Wild Bill would be an understatement. He did twice as much in half the time with Vegas as he did in 3 years with the Blue Jackets.

William Karlsson’s career stats with Columbus and Vegas from hockey-reference.com

He finished 2018 trailing only Alex Ovechkin and Patrik Laine in goals. The statistic that really jumps out at me from that whole list, however, is his shooting percentage. It tripled, going from a point and a half below league average all the way to 23.4%. How did he make such a jump? Even if you say his shot got significantly harder and more accurate, 23.4% is still an incredibly impressive number. Ovechkin, for instance, has never shot better than 14.6%. Over the past 20 years, among players with at least 100 shots, there have been 42 instances of a player with a S% at or above 20%. Only 11 of those came over the past 10 seasons.

The reason I want to talk about this is because, in short, I don’t think he’s going to repeat this performance. Statistics are fun to look at when we as fans want to argue over who was better for a season, but their biggest use comes in predicting what will happen in the future. I took a look at all the instances of players shooting at least 20% for the season and looked at what they did the following year. Based on the past 20 years, unless your name is Alex Tanguay, you’re probably in for a fall back to Earth.

Every occurrence of a player shooting at least 20% over the last 20 years. Data from hockey-reference.com

The blue line in the chart above shows the season S% that was over 20% in the timeframe. The red line shows the season following the year of 20%+ shooting, and the yellow shows that player’s career S%. In all but 3 instances, the following season brought with it a lower S%, In 19 cases, the player’s S% dipped below their career number. On average, each player fell to right around their career number. A table of the data in the above graph is attached at the bottom of this article.

What does this mean for Karlsson?

His monster season brought his career S% up to 14.6%. Based on the recent history of guys to shoot like he did, it seems like a reasonable prediction to say he drops down to that next season. Taking the same number of shots he took last year, his next season goal total would be right around 27 goals. This is something his team is going to be watching because paying a ~25-goal scorer can be very different from paying a ~40-goal scorer. That’s why it was a smart move by Vegas to sign him to a 1-year, $5.25 million contract this year as opposed to a long-term deal Now they can wait and see if he regresses to his mean before locking themselves into a big contract.

This data is just scratching the surface of the statistics available to us in the NHL today. There are so many more advanced stats being developed around zone entries/exits, shot assists, and passing that are able to give a much clearer picture of what a player does well, and what he doesn’t do well. Using the excellent data visualizations Ryan Stimson put together here, I discovered that despite his high goal total last year, Karlsson may actually be a better playmaker than scorer.

William Karlsson advanced stats, visual from Ryan Stimson

Karlsson ranked in the top third of the league last season in every stat in the “Pass Qualities” category. But in the “Shot Creation” category, he actually fell to below average in both Shots/60 and Primary Shot Contributions/60.

What about a player we know well as a pure goal-scorer?

Alex Ovechkin advanced stats, visual from Ryan Stimson

There’s a noticeable difference in Alex Ovechkin’s passing statistics. This is more in line with what you’d expect from a goal-scorer. The passes are not great, but nobody is generating shots at the rate Ovechkin is. Looking at the other player to score more than Karlsson last season, Patrik Laine, shows a chart similar to Ovechkin’s, though with fewer extremes.

Why are we looking at all this?

The short answer is it’s available. As a front office executive or a coach competing at the highest level, there is no excuse to not use every bit of information possible to give your team a competitive edge. Initially, you might look at Karlsson’s goal total and try to get him on a line with a good playmaker to set him up. But looking at the advanced stats, we see it might be just the opposite of that. Karlsson is great at generating chances for his teammates, and the team would likely benefit from getting him on a line with a good goal-scorer. Just scratching beneath the surface of the available statistics here gives us a great look at what goes into building a team, and building a team is the most exciting thing coming to Seattle soon.

Of course, I could be completely wrong here, and Karlsson really is the next Alex Tanguay, able to consistently score on 20% of his shots. Or maybe he’s just the next Anson Carter. We won’t know until we see a few more seasons from him, and that’s the beauty of hockey: no matter how much we break it down, it is still, at its core, unpredictable.

Every player to shoot at least 20% for a full season since 1998. Data from hockey-reference.com

* Editors note: Some of you may remember our series covering the rules of hockey. We loved those posts and they generated some really fun discussion. Thing is, most can be summed up in a few sentences — short of goalie interference of course (thanks Rebecca for tackling that monster). We will still gladly discuss the rules with any of you if you shoot us a message on Twitter, but we are going to shift gears here. Instead of discussing what determines a high stick, we are going to focus on hockey stats, systems, and development. This franchise is in a really critical point that will define the future for OUR team. Our goal is to help you, and us, better understand their moves. Let us know what you want to discuss and, as always, fan posts are HIGHLY encouraged. If you need help with it, let us know. - Doug