In my ongoing series, The Best There Ever Was, my comment on Bob Cousy turned into its own post about some of the difficulties of comparing player from the fifties to players from the modern game.
One problem of assigning value that I alluded to in my Bob Davies comment is that the 1950s NBA was very different from the moderns NBA in ways other than lower FG%, slower pace, and other things that can be statistically normalized. For example, the 1950s NBA was dominated by big men. By any statistical measure, almost all of the best players in the league were big men; Bill Russell, George Mikan, Bob Pettit, Dolph Schayes, Neil Johnston, Ed Macauley, and Maurice Stokes, to name some of the best. Most of the other stars were forwards like Paul Arizin, Elgin Baylor, George Yardley, and Cliff Hagan. Really good guards were a rarity. Cousy, Bob Davies, Bill Sharman, and Bobby Wanzer (for a few seasons) were excellent, but after them there were only decent players like Gene Shue, Dick McGuire, and Slater Martin, whose stats make them look like borderline all-stars instead of borderline Hall of Famers.
Why was this? One reason was the lack of the three point shot. Without the three, defenses could easily pack the paint and dare opponents to live off the 25 foot jumper. With those baskets only counting for two points, successful attempts hurt less than they do in the modern game. This is one reason good defensive centers like Bill Russell and Nate Thurmond were more valuable in the fifties and sixties than they could be in the modern game-Russell didn't have to worry about Jerry West hitting a lot of threes. I'll return to this issue in the Bill Sharman comment of the shooting guard rankings.
Another reason was the game's physicality. Some people complain that the hand check rules have made it impossible to defend quick guards, but in the fifties every kind of defensive malfeasance was allowed and encouraged on a nightly basis. In that kind of environment, the best players were usually the biggest and strongest, rather than the most skilled. This is why Larry Foust, the epitome of a "big ox", was, statistically, better per minute than Bob Cousy.
Given the big differences between fifties, big man dominated basketball, and modern, guard centric basketball, what do I do in these ratings? I don't want to simply note that Cousy (for example) was statistically rather similar to players like Stephon Marbury and Rod Strickland, and conclude that he has been vastly overrated. On the other hand, just because he was the best point guard of his era doesn't automatically make the equal of Oscar or Magic or Stockton. So, what I've done is try to imagine how the player's game would translate to the modern game, and rate them accordingly. For example, Bob Cousy was the best passer in the game, excellent in transition, a poor shooter, and a mediocre to poor defender. In my opinion, then, he deserves to rank somewhere in between Isiah Thomas (very good passer, inefficient shooter, decent defender) and Kevin Johnson (a more efficient scorer than Thomas). Feel free to complain about the imprecision of this method in the comments :)