“For marketers, the growing array of sports-related activity creates multiple opportunities to reach fans,” said eMarketer. “Digital marketers have a chance to piggyback on the active interest sports inspire in people, well beyond the games themselves.”

It’s not just that sports fans are numerous, they also post high usage numbers. In a Deloitte study of internet users’ online usage during 2011, 19% of US respondents cited “reading/watching sports content” among activities they did on a daily basis. And a year-long Experian Simmons National Consumer Study, concluded last November, found one internet user in five had gone to online sports sites within the 30 days before being questioned. Among adults under age 35, one in four did.

The expanding number of channels for sports-related content also means brands don’t have to spend a fortune sponsoring sports telecasts. “Brands can use digital channels to reach an audience of active fans,” said eMarketer. “And the large size of today’s digital sports audience makes that approach more than a marketing equivalent of ‘small ball.’”