It was very hard to decide which methods and/or stats to use to determine each great defensive player. What I attempted to do was use an array of statistics to gain an overall picture of a player's defensive capabilities. I didn't base any selection solely on one measurement, rather I used a compilation of many measurements.
The four main components used are as follows:
1) Defensive Wins Above Replacement (dWAR)
This metric is considered "all-inclusive" and is a great starting point when considering defensive abilities. It states the amount of wins one player's defensive skills have garnered above or below the league average defender.
2) Range Factor/Game
The equation here is (Putouts+Assists)/Games Played
This gives you an idea of how much "action" a player was receiving at their position per game.
In essence, the higher the range factor the more times the player was physically involved in a play during the game
3) Fielding %
I am not hardcore on this statistic, but it was useful in comparing a player's fielding percentage over their career to the league average during the same time period.
This statistic was used in addition to the others and not on its own.
4) Gold Gloves
I have never been a huge fan of the Gold Glove award. Many players have seemed to get it based on their name alone rather than on their actual defensive abilities. The fact is, when you're talking about the greatest defensive players in history, there is no doubt that they will have some Gold Gloves on their shelves.
Note that the Gold Glove was not established until 1957.