Value Over Replacement: Measuring each line and defense pair's impact on possession
Now that we've established a baseline for league-minimum players, let's quantify the value over that baseline provided by every forward line and defense pairing.
In the previous edition of this series, we looked at the talent level of players who are paid the NHL's minimum salary. We observed that they reduced their teams' Fenwick Close% by 0.52 percentage points for forwards and by 0.92 for defensemen (that is, a league average 50% Fenwick team would be a 49.5% or 49% team with a minimum salary forward and defenseman, respectively). We also noted that these are rough estimates limited by sample size, but give us an idea of the impact inserting a player with the league minimum salary (and, hence, a player who is freely available) has on a team's possession numbers.
We'll expand on that study to look at the difference between players based on time on ice percentage, or the proportion of a team's total even-strength ice time a particular player was on the ice for. It represents a reasonable way to separate players for a variety of reasons. We know that quality of teammates, quality of competition, even to some extent zone starts change with playing time, and grouping players by ice time roughly estimates these effects.
Forward Fenwick Close% Differential by TOI%
|Line||TOI%||Fenwick Close% Differential||Above NHL minimum|
Defenseman Fenwick Close% Differential by TOI%
|Pair||TOI%||Fenwick Close% Differential||Above NHL minimum|
Fenwick Close% Differential: The difference between team Fenwick Close% with the player in the lineup minus the team Fenwick Close% with that player out of the lineup. Above NHL minimum represents the Fenwick Close% differential for that tier above the value provided by a minimum salary NHL player (-0.52% for Forwards, -0.92 for Defensemen). TOI%: represents the average TOI%,(with range) used to generate average fenwick close% differential for each bin.
What the data suggests is that a top line forward (averaging a 31% TOI%), provides approximately 0.56% Fenwick Close% boost to his team, and roughly 1 percentage point over what would be expected if he was replaced by a forward who is paid the NHL minimum salary. The important point here is that we're not assuming the NHL minimum salary player takes the top line forward's ice time; this estimates the effect even if (and likely when) the NHL minimum salary player is sheltered on the lower lines.
The effect is a bit larger for a top pair defenseman. On average he boosts his team's Fenwick Close% by approximately 1 percentage point, and close to 2 as compared to a defenseman paid the NHL minimum salary. I wouldn't immediately assume that defensemen are therefore more valuable to a team's Fenwick Close%, rather that the increased ice time and reduced roster spots likely contribute to the effect, rather than absolute responsibility.
Notes on Methods
Data acquisition performed the same as the previous analysis. Lines/Pairs based on TOI% gathered from previous studies suggesting the average TOI% based on data gathered from 2013-14 lines across all 30 teams.