After decades of questionable calls and generous (or not-generous-enough) spots and players you swore were in bounds but were deemed out, the index card was what did it. Looking up from their smartphones, asking their voice-activated assistants to turn up the TV and seeing their officiating-induced elevated heart rates on their next-generation watches, incredulous NFL fans could not believe the placement of the ball after a critical 4th-and-1 in a tie Dec. 17 game between the Raiders and Cowboys was being verified by something as archaic as a piece of paper, slid between the ball and the first-down marker to justify referee Gene Steratore's first-down call. (Index cards have since been banned.)

Could the advanced technology we all have access to make that, and other improbable officiating decisions, a thing of the past? Is the NFL holding out on fans to intentionally add ambiguity to outcomes? The answer, as it so often is, is yes and no. The past few years have seen a technological revolution that could save the league and its fans a lot of frustration—and help create a more dynamic, safe version of football in the process. Actually utilizing that technology, though, isn't always an easy decision for a notoriously conservative sport.

"Three years ago, I would have said some of the sports science and performance tech was a little behind compared to other sports," said Emmett Carey, a scientist with STATSports, whose player-performance-tracking wearable technology is used by some of the world's top soccer clubs as well as the Panthers, Raiders and Bengals. "Now, it's kind of catching up."

The sidelines are full of Microsoft Surfaces, the pylons have cameras and starting with the 2017 season, the balls, as well as players' shoulder pads, have been outfitted with RFID chips designed to track position, speed and distance—the information required to bring you those infamous Next Gen Stats. Those adjustments are the tip of the tech iceberg, and teams are rapidly incorporating much more advanced tech into their practices and game-planning, where they have considerably more agency than they do on game day.

"Right now it's very much an arms race in terms of the tools and technology that can be deployed to get the most out of the team," said Matt Bairos, a CEO at Catapult Sports, which integrates wearable tech with video analytics. "Once coaches realize they can get a competitive advantage, any skepticism fades quickly. The same [coach] who only wanted to look at tape 10 years ago now need[s] all their video loaded on an iPad, so they can watch it on the flight."

As promising as that may sound, the unique challenges inherent in playing the sport have slowed the pace of tech evolution. Any innovation needs to function outdoors in all kinds of weather and withstand NFL-strength pummeling without injuring the players in the process. The players often obscure the ball entirely, making tracking more difficult. And testing new technology becomes trickier with no official development league. So the NFL takes a slow, measured approach, only introducing new features when it can be certain they won't become a liability.

Zebra, the NFL's official partner in adding chips to balls and shoulder pads, has been the most successful so far at meeting the league's stringent requirements. The RFID chip system is the same one it had already used in manufacturing and hospitals—John Pollard, VP of business development at the company, called it an "asset-tracking product." In the league's case, the assets being tracked are the players. "When we first started, the primary incentive was to use it for fan engagement—to create new stories (Think Leonard Fournette just ran 22 miles per hour) about the athleticism of these players," Pollard said of the league's decision to start tracking players' movement, speed and position in-game. "In the last 12 to 14 months, though, we've seen the teams start looking to the tracking data for player evaluation in game scenarios."

More and more teams are integrating Zebra's products into their practice regimens, including the Super Bowl-bound Philadelphia Eagles (so far, the Patriots have abstained). The goal is to find ways to use the chips' insights about performance on the scouting, training and game-planning fronts. Pollard spoke from the Senior Bowl in Mobile, Alabama, where the players were in wearables for the second time. In scouting, he said, the additional information can help teams "buttress cases for players they believe in."

When it comes to performance, wearable tech is used to track exertion and fatigue—basically using numbers to reiterate the importance of rest to being game-day ready. "In the weight room it's really easy to control and quantify effort, but on the field all the coach can control is really how long they're out there," Carey said. STATSports' Apex system (the one some NFL teams use) combines a GPS and an accelerometer to track player movement and adds biometric insights such as heart rate as well. It tracks over 50 different metrics in real time, from the number of sprints to the number of impacts. Currently, the NFL doesn't permit GPS tracking in games, while the NCAA does. "If practice is going a little longer, it quantifies what a coach would already see as far as player exertion—just to kind of reinforce it," Carey added.

Along with innovations in equipment (helmets, pads) and rule changes, tracking player performance and workload is also a way teams are trying to keep players off IR. "Live data can help staff see when a player is in an increased zone of risk for soft-tissue injury," Bairos said.

These insights aren't without cost. "The question comes up of who owns the data," said Christina Chase, director of MIT's Sports Technology Group. In particular, tracking biomedical data brings up privacy concerns. "Every athlete right now is so heavily monitored," Chase added. "What do we really need to be measuring? Will this information be used to help me as an athlete? Or when my contract comes up for renegotiation, will this be used as a way to get my contract lower or trade me away?" Carey, of STATSports, sees player education as a way to avoid feeling like "it's a Big Brother kind of situation"—but there's no question these kinds of advanced stats will become another aspect of the upcoming CBA negotiation when the current deal ends in 2020.

Players and coaches, like the rest of us, are also having to consider how information technology makes working all the time not just a possibility but also a near-necessity. At Catapult, many of their products are designed to maximize efficiency in the film room and in game-planning. "It's not the sexiest thing in the world to talk about saving time, but they're going to work 18 hours no matter what, so how much can they do in that 18 hours?" said Bairos, explaining how coaches use their technology to prioritize in-game adjustments or, "create insights from the chaos of all this data," in his words. Around 80 percent of the NFL uses at least one of Catapult's products to process the overwhelming amount of information—film, advanced stats—team officials use each week.

There's no reprieve for players, either: "As much as you need to hit the gym every day to keep your body in shape, your brain needs to hit the gym, too," Bairos said. "We provide training tools that allow coaches to not only deliver a game plan but also to assess where their players are. One team we work with sends out an assessment to players before their first meeting of the week, so they can see what each position group needs to work on." It's helping teams use the union-negotiated time they get with players more efficiently, and it's also a little bit like homework.

The more fun aspect of tech-assisted mental training? Virtual reality, which all the experts B/R consulted agreed would be an important part of football's future. "There are teams now using it to do some visualization and mental reps," Bairos added. "Especially if you're a backup, it's a way to get as close as you can to that on-field experience so that if there's an injury you're ready to perform, physically and mentally."

Right now, though, the NFL is still working on getting video on the bench. Those Surfaces have exclusively still images—play designs and All-22 images that previously existed on paper. Live player-tracking data and instant replay are two elements that, in the future, may live on sideline tablets. Catapult introduced a product in the NHL called iBench that allows players to see replays just two or three seconds after they happen. Currently, they're the only major sports league that incorporates this technology, but instant replay for everyone on the sideline seems like a near-inevitability in the coming years.

Now about those pesky chains? "Theoretically, the NFL also could use technology to get rid of the first-down markers and chains used to measure for first downs," the NFL's operations website claims. According to the experts B/R spoke with, the reasons it's not a priority are: 1. teams (and advertisers) appreciate having the break in the game to measure the ball's distance from a first down; 2. the technology required is not yet reliable or precise enough for officiating purposes; and 3. the number of debatable calls is not statistically significant enough to force the league to act. In other words, it's not worth the trouble or the cost.

That said, there's no question the technology is advancing to a point where the question of whether first downs or out-of-bounds calls are automated will soon be much more urgent. "I don't think it's crazy to say that, in a couple years, officiating will be helped by technology beyond instant replay," Carey said. "Yes, technically it's feasible," Pollard added. "What the timeline is and what specifically those technologies are remains to be seen. I don't want to speak for the league, but I'm certain there are discussions about how to use technology to enhance the efficiency of officiating. But how much of the human element do you remove?"

Even so, officials and coaches have plenty of job security according to sports tech experts. "Artificial intelligence is just not there yet," Chase said. "The technology does not exist by which a computer can make these judgments. What the technology really offers is the opportunity to take some of the guesswork out of it and reinforce the coach's or ref's decision," Carey said. "They go hand-in-hand. It's not a case where it will all be robotics, at any point."

Robot refs aside, Pollard said the next step for Zebra's partnership with the NFL is making tracking data widely available. Right now, the NFL only releases game-day player-tracking data to its own teams. "The biggest challenge is getting through an established mindset that this is too much information—this misconception that statistics and analytics are a red herring when it comes to American football," Pollard said. "Imagine having full league information available to all the teams so they can use it for player evaluation and game-planning—velocity and height of passes, sorting them by route type. Insights from both sides of the ball in all games."

When that information becomes available—as it almost certainly will—we may reach a day when all that'll be left are quandaries that not even the most advanced technologies can resolve. Like: What is a catch?