Saying that Ivory has quick feet is somewhat imprecise. He cannot dazzle from the ankles down without flexible hips and strength through his calves and hamstrings, quadriceps and core. For someone his height, Ivory does not have long legs, which allows him to run with his feet closer to the ground. Watch closely, and Ivory actually runs on the balls of his feet, almost on his toes, so he can change direction.

“The running backs with quick feet keep their shoulders square in tight spaces,” said the former N.F.L. running back Robert Smith, who is a college analyst for ESPN, “and get to the next hole without having to do a hard plant and wide leg separation.”

He added, “Chris’s feet come up and down really quickly, and he can cross his feet without losing balance.”

There is, then, an elegant quality to Ivory’s style, not unlike a heavyweight boxer’s dodging a flurry of punches. He can plow forward into a pile of mush and then bounce outside. Or, if space materializes but not where it is supposed to, he is nimble enough to adjust and find the alley.

A quintessential Ivory run, Shipp said, came in the second quarter of last week’s 34-20 victory against Washington, when Ivory darted right after receiving a toss, cut back across the formation after a hole closed up and then raced down the sideline for 54 of his 146 rushing yards.

Among running backs with at least 80 carries this season, no one averages more yards per attempt than Ivory, whose 5.54 is nearly a full yard better than the closest competitor, his former teammate Chris Johnson of Arizona (4.78), according to Pro Football Reference.

For Ivory, many of those yards come after contact, a product of his gift for almost immediately regaining his balance after getting hit. His forward lean when he runs —he presents the front of his shoulder pads to defenders instead of the tops — also makes it harder for them to knock him down. But Ivory sets up those opportunities with his proprioception, how his feet instinctively find space near him where he can step without landing on others.