What are Player Usage Charts?
Player Usage Charts, formerly known as OZQoC charts, were first introduced in the 2011 off-season to study how players were being used in a simple graphical representation. The idea caught on quickly among both hockey analysts and front offices, sparking a number of improvements.
What are Offensive Zone Starts (Horizontal Axis)?
Offensive zone starts is the percentage of all non-neutral shifts started in the offensive zone. A common misconception is that it's the percentage of all shifts started in the offensive zone, but it ignores those in the neutral zone and is therefore perhaps poorly named (liked most hockey statistics). Think of it more as a representation of whether a player is used primarily for his offensive talents, or defensive.
What is Quality of Competition (Vertical Axis)?
Quality of Competition is the average plus/minus of one's opponents over 60 minutes, except that it is based on attempted-shots (Corsi) instead of goals. Players who face top lines will have high QoC's while those with the easier task of facing mostly depth lines will have negative QoCs.
What is Relative Corsi (The Bubbles)?
Corsi, another poorly named statistic, is simply a player's plus/minus, except that it's measured in attempted shots instead of goals. In this case it's calculated over 60 minutes, and Relative Corsi is calculated relative to how the team did without him. A big blue 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 outshot badly.
What does it all mean?
Players in the top-lefthand corner of the graph are getting very tough minutes against top lines and in the defensive zone, and it's quite impressive if they don't have big white bubbles. Those in the bottom-righthand corner are sheltered against depth lines and playing in their own zone, and are usually goons. Those
What do the asterisks mean?
Since it's not generally appropriate to compare the raw usage data of a player on one team to another, which can often be like comparing apples to oranges, players who played part of the season elsewhere are marked with an asterisk.
What does the purple writing mean?
Defensemen have their names in purple to differentiate them from forwards. This is one of the great suggestions we got from an NHL executive who swears by these player usage charts.
What does it all mean?
Those on the left are defensive-minded players, and on the right offensive-minded. Those up top play against top lines, those at the bottom play against depth lines. Therefore those in the top-left are playing tough minutes in their own zone against top opponents and it's impressive if they don't have big white bubbles, and those in the bottom-right are sheltered from defensive zone play or top opponents and are usually goons. Players with bubbles that seem out of place could be misused.
Where do these stats come from?
Initially all the statistics come directly from the NHL's game files, which are processed by Vic Ferrari's time on ice site, and collected and presented at Behind the Net by Gabriel Desjardins. The idea for this graphical representation comes from Robert Vollman, with the idea for the Corsi bubbles from Eric T of Broad Street Hockey, and other developments from several others including Corey Sznajder, Josh Lile, Derek Zona, Mike Rogers, Derek Jedamski, Aaron Nichols, and Gus Katsaros.