Fleury's .947 save percentage ranks first among goaltenders who played at least 10 games in a single postseason since 1953-54. Patrick Lalime with the Ottawa Senators in 2002 and Jonathan Quick with the Los Angeles Kings in 2012 are second at .946, followed by Ron Tugnutt with the Pittsburgh Penguins in 2000 and Jean-Sebastien Giguere with the Mighty Ducks of Anaheim in 2003 at .945. Quick and Giguere won the Conn Smythe Trophy.
Since NHL-average save percentages have changed over the years, it is more informative to compare goaltenders across eras using a statistic called save percentage plus (SV+), which compares a goaltender's results to the NHL average. It is calculated by dividing one minus the League average by one minus a goalie's save percentage.
Since the average of all other goaltenders is .908 this postseason, and Fleury's save percentage is .947, Fleury's SV+ is 0.092 divided by 0.053, which is 1.736. That's higher than Quick in 2012, when the NHL average was .918 (1.518), and Giguere in 2003, when the average was .914 (1.564).
To place that result in perspective, Fleury's SV+ is higher than Ken Dryden's best postseason. In the 1977 playoffs Dryden had a .932 save percentage for the Montreal Canadiens, all other goaltenders had an average of .886, which is an SV+ of 1.676.
Being able to sustain a high save percentage through more games, and against a higher volume of shots, is one of the reasons Fleury's performance has been so remarkable. This can be measured using a statistic called Goals Saved Above Average (GSAA), which is the number of goals prevented relative to an average goaltender. It is calculated by multiplying the number of shots a goaltender has faced by the average save percentage of all other goaltenders and then subtracting that from his total saves.
