Doctor No
Registered User
These are from the just completed 2006-07 NHL regular season.
Goal Differential is a metric estimating how many goals better than average a goaltender was over a period of time. Essentially, it's a weighting of save percentage and playing time (because a save percentage of 93% is obviously much more valuable if you can sustain it over a long period of time).
It's described more in depth here: http://hfboards.com/showthread.php?t=253883
Please note that if you don't like save percentage, then you won't like these. Save percentage is not perfect (and I'm not going to defend it here).
At the behest of some people who know what they're talking about, I've removed a goaltender's shots/saves when calculating their league save percentage. In other words, if Dominik Hasek does well, that increases the league save percentage and would penalize him under this metric. Therefore, to calculate Hasek's Goal Differential, I remove his stats from the comparison set.
I've also calculated Goals Above Replacement Level, because it's not really fair to compare goaltenders to the league average. A "league average" goaltender clearly has value - many of them get several million dollars per year just to be average. Goals Above Replacement attempts to estimate how many goals a goaltender is worth compared to someone available for free (e.g., a top AHL goaltender or a free agent from Europe). Based on some conversations on the Hockey Analytics Group, I'm estimating replacement level at a save percentage 1.5% lower than league average (so if the league average save percentage is 91.0%, then replacement level is 89.5%).
Goal Differential is a metric estimating how many goals better than average a goaltender was over a period of time. Essentially, it's a weighting of save percentage and playing time (because a save percentage of 93% is obviously much more valuable if you can sustain it over a long period of time).
It's described more in depth here: http://hfboards.com/showthread.php?t=253883
Please note that if you don't like save percentage, then you won't like these. Save percentage is not perfect (and I'm not going to defend it here).
At the behest of some people who know what they're talking about, I've removed a goaltender's shots/saves when calculating their league save percentage. In other words, if Dominik Hasek does well, that increases the league save percentage and would penalize him under this metric. Therefore, to calculate Hasek's Goal Differential, I remove his stats from the comparison set.
I've also calculated Goals Above Replacement Level, because it's not really fair to compare goaltenders to the league average. A "league average" goaltender clearly has value - many of them get several million dollars per year just to be average. Goals Above Replacement attempts to estimate how many goals a goaltender is worth compared to someone available for free (e.g., a top AHL goaltender or a free agent from Europe). Based on some conversations on the Hockey Analytics Group, I'm estimating replacement level at a save percentage 1.5% lower than league average (so if the league average save percentage is 91.0%, then replacement level is 89.5%).