Key & Peele ends its three-year run tonight, and it’s a big deal. When news broke in July that stars Keegan Michael Key and Jordan Peele were stepping away to do other projects, it hit fans and critics hard. The show has rightly been called a timely successor to the gone-too-soon Chappelle’s Show for its zany sensibility and biting cultural commentary. Losing the sketch show — right on the heels of Jon Stewart’s departure from The Daily Show — is a huge loss for Comedy Central, not to mention television in general.

But where television gave Key and Peele a platform to create a show worth paying attention to, it was really the internet that turned them into superstars. While the series consistently pulled in decent ratings for Comedy Central, it attracted hundreds of millions of views on YouTube, landing its creators on magazine covers and in New Yorker profiles. TV was just the jumping off point; the internet did the real heavy lifting. Key & Peele is thus a case study in a new quandary for TV. There is a clear divide in what linear television and digital media can mean for a show, and bridging that divide as audiences move online is the networks’ next big task.

Key & Peele’s greatest strength and weakness was its format; as a sketch show, it’s best remembered for its bite-sized bits — most of which wound up online. "Substitute Teacher," which first aired in 2012, is one of the show’s earliest highlights. It quickly went viral, and right it now boasts more than 80 million views on YouTube. Earlier this year, Paramount even announced it plans on turning it into a feature-length film. But the episode it premiered on only pulled in 1.16 million viewers at the time, a drop in the bucket compared to its online views. And it makes sense, especially for a huge swath of the population that doesn’t have cable. Why wait for the show when you can watch the best clips on the internet?

Comedy Central noticed the trend and responded by pushing fans toward their TV sets in online promos. It’s not clear if the effort ever worked; ratings stayed south of 2 million over the next three years. And while fans are watching the duo deliver some of their best work this year, the show’s final season has so far gotten some of its lowest ratings ever.

The trouble with Key & Peele is that, seemingly by accident, it became a web series financed by a major cable network. Its creators could rely on the Comedy Central brand, now resurgent with zeitgeist-y shows like Broad City, to give them legitimacy. And it worked since the two comedians had the resources they needed to write ambitiously. But a show in Key & Peele’s shoes, with a streaming viewership that outstrips its TV one, necessarily forces its network to rethink what resources to put where and how to attract advertisers. It also shows how Comedy Central needed to change how it played the TV game overall. Take Inside Amy Schumer: thanks to both great writing and viewers watching on multiple screens, Amy Schumer herself has exploded into a comedy icon. Meanwhile, her show generally has even softer ratings than Key & Peele.

It’s all further proof that Nielsen ratings just aren’t the useful metric they once were — especially when it comes to the shows that are popular across multiple platforms. Key & Peele illustrates how audiences who have moved away from TV are changing how shows enter the national conversation, and what kinds of shows can enter the national conversation. As a result, they’re changing how networks need to think about traditional viewing habits altogether.

Broadcast and cable networks now have to throw out the old model for understanding shows’ success, and experiment to get a better grasp on where their viewers’ eyes go. That’s already happening. For one, The Daily Show brought The Onion’s former director of digital Baratunde Thurston on as the lead for digital content strategies. HBO also recently snapped up Vimeo hit High Maintenance for a new six-episode season. But the TV landscape is changing fast, and the internet is driving it. Maybe that’s why there’s so much TV to watch — all networks can do now is scramble to keep up.