This article in today's WSJ claims that the number of people playing baseball has grown 21% since 2014 and is the hottest sport. Sorry, it's behind a pay wall.
That corresponds to what I'm seeing.
Similar article from last year about soccer's decline:
Quote: "Yet in recent years, while soccer continued declining, baseball and basketball experienced upticks, buoyed by developmental programs begun by Major League Baseball and the National Basketball Association."