I don't think it's the decline of the US, but rather the rise of Europe (especially eastern Europe) that has taken the shine off us tennis. Today, for example, the WTA women's players, excluding Williams, are all European, and with the exception of Muguraza and Navarro, they are all eastern European (Wozniacki is originally from Poland).
There's obviously no American in the ATP top 10 anymore. The development of tennis requires a certain economic basis. As a standard middle-class sport, the investment of tennis players is huge. If it were not for the reasons of the system, li Na, Zheng Jie, Peng Shuai and other famous players could not afford training expenses in their childhood. The emergence of players has been made possible by immigration from eastern Europe and the economic recovery of eastern European countries.
So it also affected the original American members. In terms of players, although the United States could not repeat the heyday when the four king Kong dominated WTA, the United States still had the most players in the top 100 of WTA, with 12 players. ATP has eight.
Those numbers are obviously not too bad, and there are some new players, and we often see the news of us players making the most advances in grand Slams.
The United States still has the most senior tournaments in the world, including one grand slam, two WTA1000 tournaments, one 900 tournament and one 470 tournament. ATP four Masters and one 500. The spring and summer north American hard court seasons are still strong.
At the same time, the United States has the world's strongest tennis technical academy - the Knick Tennis School. Although American players are now being challenged by more and more European players, a significant number of European players also train at the Knicks. Compared with Nicki Pilic and many Spanish online schools, Nick's hard-court skills are superior.