Luke Kuechly, the magnificently talented Carolina Panthers linebacker who has announced his retirement at the age of 28, gave fans much to savour in his shortened career. It often seemed he was covering the entire field on his own, popping up everywhere to smother a running back or chase down the opposition’s star quarterback. If he wasn’t the best linebacker of his generation, he was close enough that it didn’t matter and the dizzying list of accomplishments during his shortened career speaks for itself: 2012 defensive rookie of the year, 2013 defensive player of the year, five All-Pro first teams, seven Pro Bowls, a Super Bowl appearance, league leading tackler twice, the leading overall tackler in the NFL since his debut for the Panthers nearly eight years ago. By all accounts, he was a gentleman off the field too, and the warm tributes of those who played with him, and against him, are a testament to that.

However, despite Kuechly’s myriad accomplishments, the most enduring single image of his career will not be of him taking down a quarterback or his appearance in Super Bowl 50. Instead, it will be of Kuechly being carted off the field in tears after suffering a concussion against the New Orleans Saints in 2016. His game was based on delivering crushing blows to opponents, exactly the kind of calculated violence that helps make the NFL America’s most popular league, and also makes the audience – and I include myself as a journalist and a fan – complicit in the trauma the game inflicts on players. After all, if there’s no audience, there’s no NFL.

Kuechly has never spoken about why he was in tears that day, but what we as fans saw and what it said about the public’s changing relationship with football is important. Already that season Kuechly’s teammate Cam Newton had been on the receiving end of a brutal series of tackles worrying enough for the quarterback’s father, Cecil, to wonder about the game’s effect on his son’s health. “I’m thinking about Cam Newton being healthy today, tomorrow and 25 or 35 years from now,” he said. Kuechly was a fierce competitor and his tears against the Saints may have been of disappointment at leaving his teammates behind on the field. They may have been caused by the swing of emotions that can come in the immediate aftermath of a concussion. But many wondered if his thousand-yard stare was that of a man thinking about the effects of the game on his future.

Chronic traumatic encephalopathy, a condition that can cause mood swings, depression, suicidal thoughts and memory loss, was found in 110 of 111 former football players in a 2017 study (in mitigation, CTE can only be diagnosed after death and it’s reasonable to assume families who suspected their loved one was suffering from the condition are more likely to have participated in the study). In any case, Kuechly is aware of football’s risks. “I think when you play a contact sport there’s always inherent risk and inherent risk to injury,” Kuechly told ESPN in 2017. “At what point do you tolerate it, and at what point is it enough? There’s been a lot of studies and a lot of different literature on concussion and head trauma and that kind of deal, and I think it’s a new subject that we’re constantly learning more and more about.”

In his retirement statement, Kuechly did not say concussions were behind his decision to step away from the game, instead stating that “I still want to play, but I don’t think it’s the right decision”. He did, however, suffer three concussions in three seasons although most scientists agree that it is repetitive subconcussive impacts from repeated hits that a tackling machine like Kuechly specialises in that cause lasting damage to players.

For now, Kuechly moves into retirement with his health hopefully intact. And we will continue to watch – NFL ratings are up 11% from two years ago despite a collapse in audience across traditional TV broadcasts as a whole. Even through the tears, we can’t look away.