Anyone who watched the NFL on Sunday surely saw, during the breaks between violence used to sell beer and sports betting apps, the commercial for a shaving company. It starred two handsome and impossibly fit young athletes, their square jaw lines ideal for displaying the efficacy of cutting-edge razor blade technology. When the advertisement got booked, it probably felt like a no-brainer: two cool and popular NFL stars as endorsers. When the camera zoomed on the freshly shorn faces of Saquon Barkley and Christian McCaffrey, it felt more like a giant bummer.

The NFL is not for running backs. It is by now trite to say teams should not sign them to exorbitant contracts because of how often they get hurt and how cheaply capable replacements can be found. It keeps being said because of how often great running backs get hurt after they sign exorbitant contracts. McCaffrey, one of the most thrilling and distinctive players in the NFL, became the latest Monday. The Carolina Panthers ruled him out for the season because of an ankle injury, a season in which he has played seven games, a year after he played just three.

The NFL moves fast, and the reaction to McCaffrey’s injury looked forward and peripherally. Should the Panthers tank for a better draft pick? Will the Indianapolis Colts take a pass when it comes time to pay Jonathan Taylor? What are the fantasy implications? The league is fortunate that its echo chamber leaves no space to dwell on McCaffrey’s injury and the resulting queasiness about the sport and the plight of the position.

Every NFL player is vulnerable to injury, but running backs have essentially no chance at longevity. The NFL has engineered the rule book so quarterbacks can thrive into their late 30s or longer. Nothing could make playing running back a humane profession, let alone safe from injury.

It’s punishing for the players and sad for those who watch them. Todd Gurley II was the NFL’s offensive player of the year in 2017 and voted by his peers in 2018 as the fifth-best player in the NFL. He played with a futuristic blend of power and speed whether running or catching passes. He’s now 27 and out of the league. The velocity at which running backs go from the country’s biggest athletic stars to nonentities can be jarring.

For a while, McCaffrey appeared to be a possible exception — a back who could hold up and provide value on a big contract. His versatility allowed him to receive a portion of his touches as a wideout, lessening his physical toll. David Shaw, his college coach, insisted to then-Panthers coach Ron Rivera that McCaffrey could handle a large workload because his vision and quickness enabled him to avoid the most damaging hits. He possessed such extreme and varied skill that he could not be replaced by a rookie.

The Panthers valued him as a unique offensive weapon more than as a running back, so they built their offense around him and signed him to a four-year, $64 million contract extension. McCaffrey received 326 touches in 2018 and a league-leading 403 in 2019.

Simple logic — he was their best player, so they gave him the ball and paid him as such — is actually a vicious cycle for running backs. Reducing carries might reduce injury risk but it also lessens value, and no player wants less opportunity or less money. Conserving a great running back means not using him at all, which doesn’t make sense for anyone. Teams are incentivized to take running backs in the draft, wring out as much as they can for as long as they last, and move on.

There are no exceptions. McCaffrey, like the New Orleans Saints’ Alvin Kamara, seemed like a running back who was so versatile and important that his team had no choice but to pay him and use him extensively. Derrick Henry was such an outlier in his physicality and durability that he provided hope that he could hold up. Kamara, averaging a career-low 4.7 yards per touch, has missed the past three games, and it’s unclear when he will return. Henry could return for the playoffs. In the meantime, the Tennessee Titans rushed for 270 yards Sunday against the New England Patriots, a game they lost for basically every reason save the lack of a productive running back.

With Adrian Peterson recently released by the Titans, the NFL’s active leader in career rushing yards is now Mark Ingram II, who ranks 54th. The lack of prolific backs owes in part to the league’s emphasis on passing and to the increase in speed and size of the players. The league has been able to protect quarterbacks to a large degree; running backs face even higher physical risks.

Three years ago, Peterson, the fifth-leading rusher of all time, discussed the state of his position. He emphasized the need for running backs to maximize their financial value and to hold out if necessary. He also said if he was in high school, he would switch positions and be an edge rusher. “Like Von Miller or something,” Peterson said then.

The cruel trends in how they are valued and how they get beaten up have conspired to make running back no longer a glamour position. The best athletes at every level are playing wide receiver, cornerback and quarterback. Running backs are usually not the guys who appear in commercials anymore. And when they do, it usually comes with a tinge of melancholy.