Sunny Yen isn't a big sports fan.

She's always happy to attend Super Bowl parties, but that's about it. And yet, Yen is the director of product design at a 16-person San Francisco fantasy football start-up called Sleeper.

"I look at Yahoo and ESPN, and I realized that even though I don't know about it, this is for hardcore fans only," Yen said. "I feel like they build a wall to keep the woman, female audience out."

That's why Nan Wang, the CEO of Sleeper, hired Yen and her all-female team to design the look and feel of his company's website and app. Appealing to women, casual fans and first-time fantasy players is critical to Sleeper's strategy.

This more inclusive approach has informed features that Sleeper hopes set it apart, including the color coding of player stats and a simplified league set-up process that can be done in 30 seconds.

"The only way you can do that is to think outside of the box," said Wang, highlighting that nearly half of his employees are women and most of the employees don't really watch sports. "We consciously made that hiring decision."

In fantasy sports parlance, a "sleeper" is an under-the-radar player that has the potential to outperform his more established counterparts. That's how the start-up sees itself in taking on Yahoo and ESPN.

"We feel like we're that breakthrough talent," Wang said. "We're the underdogs in this space competing against some big names, but we have the right talent to do so."

The start-up also chose the name because it was gender neutral and welcoming, Wang said.

"We saw a lot of other sports companies come out of the gate with names like 'Draft Monster,'" Wang said. "We thought a lot about inclusivity. Even our icon is half cute, half sporty."