Understanding Context with Player Usage Charts
When studying hockey statistics, context is everything. It's common knowledge how a player's stats can be greatly influenced by his playing conditions. Factors such as their line mates, opponents, and goaltenders, not to mention the manpower situation and the score, can all skew a player's stats one way or the other. Player Usage Charts put a great deal of that information into simple graphical form.
For example, if you've ever wondered how Henrik and Daniel Sedin could go from below the point-a-game rate in their mid-20s, all the way up to sudden Art Ross, Hart Memorial, and Ted Lindsay award winners in their older age, and then right back down after Vigneault's departure, then look no further than Player Usage Charts.
Years ago these charts reveal Vigneault's tendency towards a style of aggressive zone-matching that results in players like Manny Malhotra getting all the shifts that start in the defensive zone and Ryan Kesler taking on all the top lines, thus leaving the Sedins to start their shifts primarily in the offensive zone and against fairly average competition. Their offensively potent seasons were as predictable then as Mats Zuccarello's are now.
Even though Player Usage Charts can eloquently show how a team's players are being deployed, there's a lot of complexity under the hood. A lot of raw data is mined from the NHL's official game files, and organized into each concise picture.
Ideally the end result is easy to understand with very minimal explanation. The horizontal axis features the player's offensive zone start percentage, which is the percentage of all non-neutral shifts started in the offensive zone (not counting on-the-fly line changes).
A common misconception is that it represents the percentage of all shifts started in the offensive zone, but it actually ignores those in the neutral zone, and is therefore perhaps poorly named (like most hockey statistics). Think of it more as a representation of whether a player is used primarily for his offensive or defensive talents.
Getting a lot of offensive zone starts will result in more favorable scoring totals, and for very obvious reasons. Starting in the offensive zone means that a faceoff victory can lead directly to scoring opportunity, whereas winning in the defensive zone still required someone carry it out and down into the offensive zone before a shot could even be attempted. It's therefore no surprise that each extra offensive zone start has been calculated to be worth an extra 0.8 shots in a player's shot-based plus/minus.
On the vertical axis, you'll find the player's Quality of Competition. This can be measured in a variety of ways, such as using the average ice time of one's opponents, but he results are normally the same. Here it is being calculated based on the average plus/minus of one's opponents over 60 minutes, except that it is based on attempted shots instead of goals. Doing that filters out the effect of goaltending, and all that extra data serves to reduce the impact of a few bad bounces.
Regardless of which measurement is used, those who face the top lines are always at the top of the chart, and those who face mostly depth lines are at the bottom. Of course, bear in mind that these charts reflect the entire 82-game schedule, whereas line matching is only realistically possible on home ice where the coach has the final change.
Finally, there are the big shaded circles around each player's name. These names sometimes include asterisks, incidentally. A prefix means the player spent the first part of the season somewhere else, and a postfix means the player finished the season somewhere else. Given how some teams, like Los Angeles, start a lot more shifts in the offensive zone than others, like Toronto, it's important to take note of which players stats might have been steered one way or another.
As for those circles around the names, they are shaded and sized based on the player's attempted shot-based plus/minus, with two important adjustments. First, it is calculated relative to how the team did without him, so that players on weak teams don't get penalized, and players on great teams have to prove they're not just riding someone's coat tails. Secondly, the size of the bubbles are calculated over 60 minutes in order to neutralize the advantage of those who get more ice time. And remember that all this data is in five-on-five situations only.
Ultimately, a big shaded bubble represents someone whose team attempts a lot more shots than their opponents while he's on the ice and a big white bubble is someone whose team is usually getting badly out-shot. This is important given the correlation between attempted shots and concepts such as zone time and puck possession.
Always remember that the whole point is to establish context, not to claim that one player is better than another. Players are used however they are for a variety of reasons, many of which can be outside their control. One thing to keep in mind, however, is that anyone playing tough minutes in their own zone against top lines should have their white bubbles excused, while we shouldn't necessarily be too impressed by big shaded bubbles if it's for someone who is enjoying easy minutes in the offensive zone and against depth lines.
So what's the bottom line? Players on the left side of the chart are defensive-minded players while those on the right are focused on scoring. Those at the top of the chart are up against the top six, while those at the bottom play against depth lines. These key pieces of information can help put everyone's scoring totals in the proper context, and help predict the season to come.
This being the first season that Player Usage Charts have been included, we have included a brief analysis to help interpret each one. Be especially on the look-out for any player whose scoring may be dependent on favorable playing conditions that are unlikely to continue, or those who blossomed despite a tough assignment.