I've been playing around with my win threshold stat lately. Through the Hockey Summary Project and as a result of a new book by Sebastien Tremblay, we now have shots against data for every NHL season since 1954-55. That opens the door for a complete statistical analysis, both at the team level and at the individual goalie level.
Since the primary focus of this blog is team effects on goalies, that was the first area I looked at. Here are the correlation coefficients between each team's win threshold and save percentage (both figures adjusted for league scoring levels):
The Original Six Era (1955-1967): -0.545
The Expansion Era (1968-1979): -0.394
The Open Eighties (1980-1990): -0.306
The Talent Influx* (1991-1997): -0.133
The Dead Puck Era (1998-2004): -0.081
Post-Lockout NHL (2006-2009): 0.014
Over most of the NHL's history, the teams that scored the most goals and prevented the most shots have also tended to have the goalies with the best numbers. It is only over the last two decades that we have seen increasing independence between team results and goalie results. That is not to say that there is none of that in recent years, simply that when looking at the overall picture we would expect more of a team impact on the numbers of a goalie playing in the 1960s or 1970s than on a goalie playing today.
Part of this could have been that the better teams had more of a tendency to develop or acquire the top goaltenders in the past. However, the evidence to me suggests that shot quality effects are mostly determined by differences in skill rather than differences in style of play, and therefore shot quality effects are going to be largest in an unbalanced league with large differences in skill between the top and bottom teams. That is supported by the data above, since in today's salary-capped league we don't see the same degree of goalie/team stat dependence, whereas in leagues that were more unbalanced because of factors like expansion, territorial rights or management competence, the goalie and team numbers are far more intertwined.
I have a few posts coming up on the topic of win thresholds, including which goalies had the lowest and highest career numbers, the importance of goaltending through different periods of league history, and how well win threshold numbers predict playoff results.
(*-I'm planning to look at a few different metrics broken down by era, and I wasn't really sure what to call the transitional period between the high-scoring 1980s and the low-scoring late '90s/early '00s. I'm not aware of any term that is in common use to describe the period, but if there is hopefully somebody can let me know. In my opinion the most defining part of the early 1990s was the migration of new talent into the NHL that really broke the Canadian dominance of the league. More Americans started playing the game at the highest level, while the fall of communism and escalating player salaries also attracted more of the top European players. At the same time, there was an overall improvement in the level of goaltending around the league, with a new generation of goalies breaking in and mostly displacing the generation before them.)