Before 2007/2008, the 3rd spot on the rankings was generally shared between Davydenko, Roddick and Nalbandian. The second spot was occupied after Nadal pushed himself to the top of the rankings. He was so consistently good he, himself, as #2, had enough points to lead the rest of the tour as a dominant #1 in a different era. Then in 2007, Djokovic came along and claimed the 3rd spot, once again having enough points to be a dominant #1 in a different era. Then Murray comes along with also enough points to be a dominant #1 in another era. What's happened is that there are four DOMINANT #1 players. They would all be #1 in another era and they're all talented enough to be all time greats.