Manning is old and hurt. He underwent spinal-fusion surgery in 2011, which facilitated the end of his illustrious career with the Indianapolis Colts (featuring a Super Bowl title and four Most Valuable Player awards) and the beginning of his accomplished late-career run with the Broncos (a Super Bowl appearance, another MVP). The operation led to immediate changes in his abilities and tactics—wobblier spirals, shorter passes, a heightened disinclination to take big hits—but those changes have since been magnified to an extreme.

Some of his passes this season have been torturously slow or misaimed, and he curls and tumbles at the approach of a defensive lineman as if to protect a skeleton made of chalk. In late summer, near the end of the preseason, Manning admitted that the fingertips of his throwing hand have been numb ever since his return four seasons ago, and in September, ESPN The Magazine ran a profile of the player in which the normal routine of undressing after a game was revealed to be more arduous to him now than throwing an out-route against a top-flight defense once was.

From the perspective of pure football, the present situation of Manning and the Broncos is an interesting one. Despite Manning’s struggles, Denver holds a record of 6-0. A league-best defense and a cadre of highly skilled receivers, once considered networks of support to their quarterback’s distinct genius, now do most of the weekly work, with Manning chipping in where he’s able. One effect of this inversion of roles is that the Broncos seem somewhat anachronistic, a low-scoring and hard-hitting team in a league built (owing in no small part to Manning’s own influence) on prodigious passers.

But because football is a grim and violent game, Manning’s swan song is no harmless experiment. Each of his drop-backs triggers a hint of fear, from the viewer if not from the player himself. The words spine and neck linger, and nightmare scenes of paralysis flash. His slow and lanky limbs seem ready to fall apart at the slightest knock. Manning once stood for a certain kind of football future, chess played with human bodies—hazardous, sure, but fundamentally artful and intellectual. Now he stands for the game’s very real and very dangerous present.

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In the prime of his career, Manning seemed lab-built to fulfill the needs of the NFL, in regards to both the evolution of the sport itself and its family- and advertiser-friendly, corporate-synergistic sheen. He was a generational talent, and an even rarer character in the ongoing story in which football positions itself as an outlet for American gumption. The old, hard times called for hard heroes, men who hit and scowled and spit out their teeth, but by the end of the 20th century and the start of the 21st, the nature of the country and its appetite for injury as entertainment had changed, however slightly. Football needed a star who could make its virtues—hard work, leadership, sacrifice—more modern, and maybe a little gentler.