Or as was pointed out up thread they may be subjectively judging it based on the seeming slip in her singles play while her doubles play has remained strong.
Dseid, you are looking at a paraphrase written by a reporter and acting as if it is the official position of the USTA. And then demanding proof that it’s not their official position just as icing on the cake. That’s no way to be, broseph.
Also true.