The NFL Network may be crowing about having full distribution in the U.S. for the first time in its existence, but it sees its mobile app as one of its biggest revenue-growth opportunities.

For hardcore NFL fans, especially those who play fantasy football, TV has become the "second screen," according to Manish Jha, the league's general manager of mobile-media initiatives. Now, Mr. Jha is restructuring the league's signature mobile app in an effort to turn this highly engaged mobile audience into a significant revenue stream.

NFL Mobile is selling pre-roll inventory for its on-demand videos for the first time this year, he said. The app will also be serving fewer banner ads, instead opting to run more of the Interactive Advertising Bureau's "Rising Stars" ad units, which are larger and more interactive. The inventory will be sold directly as opposed to through an ad network, he added.

Perhaps the most important initiative has been making NFL Mobile accessible to all smartphone users. The league's flagship mobile app was previously only available to Verizon customers, thus forcing the NFL to create a separate app for consumers on AT&T, Sprint and T-Mobile.

Having just one NFL app has several advantages, Mr. Jha said, the foremost being easier discovery within the Apple App Store and Google Play. The consolidation also allows for more efficient way to serve ads and collect user data across different devices and operating systems.

Verizon will retain exclusive rights to live streaming of games on mobile devices, however. A company spokesman said in an email: "The premium content available on Verizon Smartphones, including access to live games ... along with the NFL network 24/7 and NFL Redzone, is content that will drive customer loyalty and motivate others to switch to Verizon."

That streamed content can be a key competitive advantage. While a consumer switching carriers just so he or she can subsequently pay a premium to stream games on a 5-inch screen may seem far-fetched, don't underestimate fantasy football players' seemingly insatiable appetites for all things NFL.

Tom Brady -- the NFL's VP-content, not the New England Patriots quarterback -- said that fantasy football players consume seven times more NFL-related media than fans who don't play fantasy. Such fans bring their laptops and/or tablets to sports bars every fall Sunday so they can meticulously track fantasy stats over hot wings. They have a subscription to NFL RedZone so they can watch four games simultaneously via the show's Quad Box and never miss a touchdown. They religiously check injury reports on their smartphones each day while listening to NFL Network's Rich Eisen crack jokes with Larry David on Mr. Eisen's NFL-centric podcast.

"Second screening" typically means using a mobile device to access information complementary to what's occurring on TV. For the NFL's most dedicated fans, its the inverse: What's happening on TV complements the pixels in their palms.