The closing ceremonies at the 2016 Olympics in Rio. Image source: Flickr user David Jones.

The Olympics are like steroids for news networks. People generally uninterested in sports still want to know how their countries' athletes are faring at the Games. And with more and more people getting their news from social networks like Twitter (NYSE:TWTR) and Facebook (NASDAQ:FB), the 2016 Rio Olympics represented one of the biggest opportunities of the year for both companies to drive engagement and ad revenue.

The two companies rolled out ways to follow the Olympics on their platforms, and Facebook introduced photo filters and frames for fans to show their support. So how did users respond to the social networks' big push?

Impressions versus engagement

Fortuitously, Facebook and Twitter released data on how their users followed the Olympics on their platforms. Twitter highlighted its total reach, while Facebook pointed to its engagement.

Twitter says it saw 187 million tweets about the Olympics, which produced 75 billion impressions both on Twitter and around the web. On Facebook, 277 million users interacted with Olympic-related content 1.5 billion times; on Instagram, 131 million users made 916 million "likes" and comments on photos and videos of the Olympics.

There are some valuable conclusions we can draw from those data.

The growth in content from Twitter is underwhelming. During the 2012 games in London, Twitter saw 150 million tweets. It only had 167 million monthly active users back then, and it has 313 million MAUs today. That indicates that still only a small percentage of users on Twitter are producing content, and that percentage has shrunk significantly over the past four years.

We can also see that engagement on Instagram is much higher than on Facebook. Facebook has about 3.4 times as many users as Instagram, but only about twice as many users interacted with Olympic content. Additionally, users who interacted with Olympic content on Facebook were less engaged than on Instagram. Instagram produced nearly seven likes or comments per user who interacted with Olympic content; Facebook produced 5.4 likes or comments per user.

Interestingly, Facebook focused its engagement efforts largely on its flagship platform. It even offered a Moments-esque curated feed of content for users to follow the Olympic games.

Who won gold?

It's hard to say if either company performed well. Twitter's massive decline in tweets per user (0.6 vs 0.9) is troubling, but indicative of a broader trend analysts have pointed to before. Facebook, on the other hand, doesn't have any comparable statistics to make strong assessments.

What stands out, however, is the engagement rate on Instagram, which bodes well for Facebook investors.

During Facebook's third-quarter earnings call, CFO Dave Wehner told analysts that ad load on its flagship platform is near saturation. As a result, he expects ad revenue growth to slow starting next year as it loses a key lever.

Importantly, ad load on Instagram is still relatively low. The company just opened its ads API to small businesses a year ago. The fact that Instagram users are generally more engaged with content on the platform than Facebook users shows the potential for Instagram to charge higher prices per ad on Instagram than on Facebook. Many reports indicate that the average price per ad on Instagram is already higher than on Facebook, but that doesn't account for lower-value right-hand-column ads on Facebook's desktop site driving down average Facebook ad prices.

Nanigans, an Instagram ad partner, says the cost per click of an ad on Instagram is three times higher than on Facebook, but that's a result of lower ad engagement. Cost per impression is actually lower; that may be due to the large concentration of branded advertising on Instagram, compared to direct-response marketing on Facebook. Branded advertisers care more about impressions, while direct-response advertisers care more about clicks.

The point is, there's room for improvement in Instagram's average ad prices. With the Olympics generating outsized engagement on Instagram compared to Facebook, it's clear that there's a lot of value in Instagram. It deserves a gold medal for its Olympic Games performance.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.