Tennis used to rank like college football before the BCS.
Players were judged by the media and by so-called experts in the field. What is more, players were generally ranked only at the end of the year.
This is kind of like the Associated Press looking back over the year in 2002 and announcing that Ohio State, in its opinion, was the best team in college football.
Let us just admit that the old college system was a very arbitrary and imperfect means of ranking.
In tennis, with the rise of the ATP and the WTA, the rankings began to evolve into a system based on wins, weighted by the difficulty of the event.
For the men, such a system began in 1973. For the ladies, their ranking system began in 1975.
Rankings today are updated weekly based on tournament results. While the system still has its critics, it remains consistent and fair in most people’s estimation.
Prior to the Open Era, there were many great players who dominated for lengthy periods of time, like Aussies Rod Laver and Margaret Court or players like Bill Tilden and Helen Wills Moody from the United States.
But starting with the Open Era, we have a body of substantial evidence to determine the length and breadth of the following players’ periods of domination—15 men and women who seized control and held it for an extended period of time.