Sunday will close the book on a small but significant era of NFL football: the early-season days when NFL games would take place on the infield dirt of dual-use stadiums.

Oakland’s home stadium — it’s now called RingCentral Coliseum, but you wouldn’t have guessed that if I’d given you a hundred chances — will see its last Raiders game Sunday with the infield dirt from the A’s still in place. Oakland’s next “home” game is in London, and between byes and road trips, the Raiders won’t return to Oakland until after the baseball season’s over. And Oakland is the final dual-use baseball-football stadium still hosting games in the NFL ... for a few more weeks, at least.

That’s a tiny tragedy, if only because it means we’ll never again get the deeply weird visual of a running back skittering out toward right field, a kick returner picking a route right over the pitcher’s mound, or a quarterback rolling out to deep short.

If you’re of a certain age, you remember the era when games across the country were played in squat futuristic donuts like Atlanta-Fulton County Stadium, Jack Murphy Stadium in San Diego, Riverfront Stadium in Cincinnati, Three Rivers Stadium in Pittsburgh, Busch Memorial in St. Louis — ugly modernist circles that hosted both baseball and football teams. And since baseball season ran into the opening weeks of football season, even for terrible teams like the mid-70s Braves or the mid-90s Pirates, you were guaranteed to see some beefy corn-fed massive-shoulder-padded monster drive a running back with a neck roll as thick as your thigh into the unexpected russet brown of infield dirt.

Here’s a pretty cool video from a few years back about how the transformation takes place in Oakland, from the last out of a baseball playoff game to the kickoff of a football game:

Those days are gone forever now. Both NFL and MLB teams figured they deserved their own playgrounds, and all over the country teams managed to talk cities into building two separate monoliths. Moreover, both baseball and football fields have about as much in common with your front yard now as you do with an actual NFL player. The precisely engineered chemical compounds that make up today’s fields are a far cry from the back-up-the-dump-truck, here’s-a-load-o’-dirt days of yore.

In the grand scheme of sports, it’s really for the best that players aren’t slamming into each other atop chewed-up infield dirt. Old-timers will tell you of how they’d grind opponents’ body parts into the rock-strewn infield, and picking pebbles out from under your skin was a regular part of any postgame locker room rehab.

So, farewell, infields on football fields. We’ll miss you, if only because watching NFL players get stomped into the dirt made it seem like they were just like the rest of us, if only for one play.

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Jay Busbee is a writer for Yahoo Sports. Contact him at jay.busbee@yahoo.com or find him on Twitter or on Facebook.

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