Taylor Fritz has been out of the US Open for nearly a week—and he’s already back to ranting about the quality of tennis balls.

In a 500-word post Thursday, Fritz complained about the difference between the Wilson US Open balls used during the tournament compared to the ones available for public purchase.

“My last two days of practice with Wilson US Open balls have been miserable,” Fritz wrote. “They are sold, marketed, and labeled as the same balls, but the way they come off my racket and feel couldn’t be more different.”

Fritz said that he had “no complaints” about the Wilson balls used at the US Open, or even at the DC Open and Cincinnati Open. He described the balls he’s been using recently as “incredibly soft, dead, and going nowhere.”

He said he’s even tried multiple batches of Wilson US Open tennis balls, but they’ve been “the same across the board.”