Comparing eras just is impossible. There are so many variables that define an era that others did not deal with. Many people like to throw out stats, but the truth is you can make stats cases for the people I mentioned above. You can pick and choose stats that will make a case for each player.
We will never know who the greatest of all-time happens to be. We should just enjoy each players accomplishments without tearing apart others. Each player brought something special to the table. Defining the greatest of all-time is virtually impossible so we should stop trying.
