Here is a glossary of statistical terms used in my various posts:
Corsi – This stat refers to measuring shots + missed shots + blocked shots as a measure of puck possession. It can be applied to the team level, but also the individual level. For teams, it is usually a simple counting stat. For players it functions similarly to the +/- statistic, where whenever a player is on the ice for an even-strength (Shot on goal/Missed Shot/Blocked Shot) for his team, he is credited +1, and whenever he is on the ice for an even-strength (S/MS/BS) against, it’s -1. Then, that number is normalized and expressed per 60 minutes to account for time differences between players. For individual players, the simple counting method doesn’t tell us that much besides how many minutes a guy plays, which is why it’s expressed per 60.
Example: The puck drops to start the game. Mikko Koivu wins the draw cleanly and passes to Ryan Suter, who skates down the ice and fires a shot that misses the net (+1). Zach Parise gathers the puck and shoots it on goal (+2), where the goalie *waffleboards it into the corner* and the opponent picks up the puck, skates back down the ice and shoots the puck (-1, net +1) but it is blocked by Marco Scandella. At this point there is a whistle. All the Wild skaters that were on the ice have a +1 Corsi right now and all the opponents that were on the ice have a -1 Corsi.
Corsi Relative (Corsi Rel) – This takes the individual corsi stat described above and expresses it relative to the other players on the team. We take the Corsi of a player when he is on the ice and compare it to the cumulative team rating when he is off the ice. For a simplified example, imagine Gordie Howe’s Corsi on-ice was +10, while when he was off the ice, his team was collectively -5. Mr. Hockey’s Corsi Relative would be 15.0, reflecting that he was very involved in driving his team’s possession and shots. This statistic helps us understand a player’s involvement compared to the rest of his team. It’s a simple idea that gets a little more complicated because we only look at 5v5 and Ev Str. Click here to view 2011-12 Corsi Rel leaders.
Corsi Relative Quality of Competition (CorsiRelQoC) – Once we understand what Corsi Rel means, we can look at a player’s level of competition faced, expressed in terms of average CorsiRel. Since we can track exactly who was on the ice for each shift, we can average together all the Corsi Rel’s for a player’s opponents, weighted by minutes. The resulting number can be positive or negative, with scores close to zero reflecting average competition, while scores above +/- 1.0 indicate very stiff or very soft competition, respectively. This is a very helpful statistic in that it helps provide context to a player’s Corsi Rel. For example, a player who manages, let’s say +12.3 Corsi Rel with a .964 Corsi Rel QoC can be objectively said to have driven possession and shots against difficult competition, where a player who turns in a -5.6 Corsi Rel with Corsi Rel QoC of -0.434 got outshot by weaker opponents, possibly the other teams’ depth players or checking lines.
Fenwick – Basically, Fenwick measures a team’s offensive production using the sum of shots plus missed shots. It is most commonly expressed as a ratio out of 100…for example. if Pittsburgh fires (40 sh + 20 msh) and Detroit only gets (30 sh + 10 msh) we would measure that as .600/.400 PIT. Fenwick provides a broader look at team production than simply looking at shots on goal. For more reading, see “Understanding Advanced Stats, Part One: Corsi and Fenwick”
Zone Starts (OZ%) - This is a simple statistic that measures the proportion of shifts that start in a player’s own defensive zone vs. his offensive zone. We throw out neutral zone faceoffs and just look at offensive/defensive starts for a cleaner measure of a player’s role on his team. It is represented as the proportion of offensive zone starts out of the sum of (offensive zone starts + defensive zone starts).
The goalie stats below were developed by Rob Vollman (@robvollmanNHL) for his Hockey Abstract website.
Bail-Out (BO) - a game in which the goalie posts a non-Quality Start, but his team still comes away with the Win.
Quality Start (QS) – defined as a start where a goalie’s Sv% was above .913 prior to 2009-10, and .917 since then…OR…a start where a goalie gave up 2 or less goals and had a Sv% > .885. The idea is that Wins as a stat for goalies can be misleading, and that to assess true goalie performance, one should focus on the goaltender’s main job, blocking shots. Rob crunches the numbers and determines the benchmarks to use–he found that teams win about 78% of games in which a goalie has a QS.
Quality Start Wasted (QSW) - a game in which the goalie posts a Quality Start but his team loses the game.
Terrible Start (TS) – the counterpart to a Quality Start, defined as a start where a goalie’s Sv% is < .850. Vollman termed these “Really Bad Starts” (RBS), but I prefer to call them Terrible Starts, mostly because I think the acronym TS is more descriptive >_>
Terrible Start Bail-Out - a game in which the goalie has a Terrible Start but the team gets a Win. These are very rare, unless your name is Pekka Rinne.