How to evaluate the historical position of Fernand?

I used to think Federer was the most dominant, but Denial Jr changed my mind in the past two years. First of all, Dejo is great, so is Nadal, and so is Federer. I want to say something that has nothing to do with evaluating the historical status of the three people. I read an article that the five most influential male tennis players in history are 5 Agassi, 4 Deyo, 3 Sampras, 2 Nadal, 1 Federer. I don't know how this ranking came from, and the most influential ones are hard to define. I think it should be added that since 1990s, Laval, mcenroe, Bjorberg, Connors and Rendell are also great tennis players of their time. Of course, due to the long time, most of them are learned from some videos and pictures. However, since the 1990s, due to the popularity of TV broadcasting, players' impressions are not vague. Let's start with Agassi and Sampras. They are almost contemporaries. In the early stage of their career, they faced such masters as Edberg, Becker and Corell, and they are also famous in tennis. In the mid-1990s, a number of top players emerged, such as Kafirnikov, Rafter, Moya, kuerten, Rios and Ivani Savage. enquist, Rusedski, Kodak, Piolin, Henman, Bioque Man, Zhang Depei, Krajicek, Norman and other strengths should not be underestimated. At that time, it was a great achievement to win two Grand Slams a year. Hewitt, Safin and Norman entered the new millennium. When Sampras retired, people thought that 14 Grand Slam was almost the limit of tennis players. Unexpectedly, this limit was broken by Federer, followed by Nadal and then Germany. A few years ago, Federer's 20 championships were the limit anyway. Now Nadal is tied, Djokovic is one crown short, and Djokovic has a high probability of exceeding 20 crowns. It's like watching Sampras' 14 crown in early 2000. It's hard to say whether there are any latecomers after the 20 th crown. Therefore, it is difficult to judge whether Guan Gong or Qin Qiong is greater in different times. At least, these three people represent a ruling period. However, in the 1990 s, the style of play blossomed. After 200 1, in order to make the game more enjoyable, the court began to slow down. Combined with the development of racket technology, the first players almost disappeared. Take Sampras for example, his style of play is hard to win at Wimbledon now. Nowadays, the racket is easier to pull out the powerful topspin and hit the cross easily. Similarly, if the current baseline players are allowed to play according to their conditions in the 1990s, the world ranking around 10 will be solved by serving (not necessarily correct), and the impact will be hard to say.