Facebook might have a deal with Major League Baseball to officially stream 20 games this summer, but unofficially games are being pirated across the social network all the time, as stolen sports plague live video channels and private groups.

Piracy, while nothing new, poses a greater challenge than ever to Facebook because of its fledgling video hub called Watch, in which it hopes to attract top media partners. It specifically needs solid relationships with sports leagues like MLB. It's impossible to know if the number of pirate streams are growing or exactly how much piracy has infiltrated the network.

However, sports are big business on digital platforms, where the National Football League charges $50 million for the right to run just 10 of its games. Meanwhile, the ease of piracy has made games freely open on Facebook live and YouTube, where the problem has been well documented, too.

"This is billions of dollars at risk here," said Eric Feinberg, a former marketing executive, who now tracks content on digital platforms. "Pretty much every NFL game is being streamed live on Facebook and YouTube for free."

Feinberg, a frequent and vocal critic of Facebook and YouTube, has been documenting pirated games over the past couple months. Feinberg often monitors the platforms and calls out nefarious activity, and was one of the voices that pushed YouTube to tackle terrorist videos earlier this year.

In the past few weeks, Feinberg has found New York Yankees and Mets broadcasts played on shady overseas Facebook pages and in private groups.

Facebook accounts like ProStickz Gaming TV streamed live NFL preseason games, and they often host links to outside websites like typical spammers. Essentially every pre-season NFL game has been available through Facebook live streams from shady accounts and through similarly nefarious YouTube channels.

When one stream gets taken down, another one often pops up, as happened with a Tampa Bay-Jacksonville game. Accounts with names like Sport America and Sport Stream Center would start broadcasting when Facebook caught the original stream, and this way people could hop from removed video to removed video to stitch together a whole game.

"Facebook does crack down, after an hour or half hour, if enough people report the piracy," said Chris Pavlovski, CEO of Rumble, a video rights management company. "But they're not actually looking in-stream in real time. That's where they need to get smarter."

In other examples, a Dolphins-Ravens game, seemingly streamed from a regular Facebook user's account and reached almost 500 viewers. Meanwhile, an Eagles-Bills game was streamed to a Facebook Group called "NFL 4 The Real Fans."

On the baseball front, an account named PuraKuraTV streamed Los Angeles Dodgers games. The Dodgers charges cable companies $5 a subscriber to broadcast its games, television rights that cost billions of dollars.

PuraKura also streamed Mets-Yankees games and Red Sox-Cardinals, Feinberg said.

"We devote significant resources to address copyright issues for live content on Facebook," a Facebook spokesman said in an e-mail statement. "This remains a work in progress and we continue to listen to feedback from our partners to help improve our offerings."

Earlier this month, Facebook acquired a content rights startup called Source3. It's also developing better artificial intelligence and hiring more human monitors to help review content.

YouTube has similar issues where live streams of entire networks, including cable news, appear on the platform. Earlier this year, following an AdAge report, YouTube made it so new channels couldn't start making money from the ad-sharing program until they reached a threshold of views. It was meant to give the platform time to sniff out bad channels and shut them down before they could make money.

The problem persists, however, and even big-budget movies like "The Mummy" and "The Fate Of The Furious" have streamed on YouTube. YouTube also has a lot riding on relationships with premium networks and content creator to help populate the site with quality videos.

YouTube and the NFL declined to comment, and MLB did not return a request for comment.

Facebook does not make it as easy for newcomers to share in ad revenue, so the economics aren't as simple as they are on YouTube. Still, Facebook is developing revenue-sharing programs, and pirates use their illicit streams to build networks of spam that can make money off of Facebook.

Feinberg said another test for the platform will come when the NFL regular season starts in September. Also, the Floyd Mayweather-Conor McGregor fight will be be a prime target for pirates, because it will cost honest-paying viewers $100.

"The one basic thing I learned when I was seven years old, listening to Yankees games," Feinberg said. "I go back to Mickey Mantle on my radio. 'No rebroadcast, retransmission without express written consent'."