Who is the fastest RB in the NFL in 2021?

That is an interesting question: who is the fastest RB in the NFL today? How do we figure that out without a foot race between every NFL RB? Is it solely based on who has the fastest 40-yard dash time?

If that is the case, then the fastest active player based on their 40-yard dash before the NFL Draft would be WR John Ross of the New York Giants. He ran a 4.22, an NFL Combine record to beat RB Chris Johnson's long-standing record of 4.24.

WR Marquise Goodwin has the second-fastest time of 4.27, but he also qualified for the 2012 Olympics in the long jump event. In trials, he had a mark of 8.33m, and it would have won him gold if it was in the final. Goodwin ended up finishing 10th in the final, though.

As for RB, San Francisco 49ers' Raheem Mostert ran a 4.32, 10th-fastest among all active players and the top time for RBs.

Raheem Mostert.That's it. That's the tweet.#BeLegendary pic.twitter.com/xirNLEvbBF

— San Francisco 49ers (@49ers) January 20, 2020

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What is the fastest speed during a live NFL game?

Are we talking about the fastest speed clocked during a live NFL game? Thanks to the NFL's Next Gen Stats, which has revolutionized the analytics of pro-football, we can analyze just that.

With their technology, they can track a player's speed as they run down the field, and mark their top-end speed. During the 2020 NFL season, who had the fastest speed clocked on the field?

The fastest top-end speed for a RB was from San Francisco 49ers' Raheem Mostert, who had the first and second fastest marks: 23.09 mph on an 80-yard TD run and 22.73 mph on a 76-yard receiving TD play. His 40-yard dash time was 4.32, the fifth-fastest, which he ran back in 2015.

A reminder that @49ers running back Raheem Mostert reached the two fastest speeds by a ball-carrier last season.🔹 23.09 mph in Week 2 (80-yard TD)🔹 22.73 mph in Week 1 (76-yard TD)The rest of the top 5: pic.twitter.com/xtFZWkNmV6

— Next Gen Stats (@NextGenStats) May 6, 2021

Let's swing back to the foot race idea, as several NFL players have actually done just that. WRs Mecole Hardman, Henry Ruggs lll, Justin Jefferson and LB Devin White raced in a 40-yard dash back in May 2021. Hardman won the race with a 4.22, tying John Ross' official time. Mecole Hardman had a top-end speed in the NFL playoffs in 2020 of 21.52 mph on a 50-yard run.

So who's the overall fastest NFL RB? It's not a perfect science, but Raheem Mostert is the best candidate. How fast is his 23.09 mph compared to the rest of the sports world?

Take a look at Usain Bolt. WR Tyreek Hill had a beef with the Olympic sprinter, and there is $1 million on the line if they ever do race. Bolt once ran a 40-yard dash during a Super Bowl event in 2019 in 4.22 seconds, tying the NFL Combine record. His 9.58-second 100-meter dash time equates to a 3.99-second 40-yard dash, while his top-end speed was 27.78 mph at his finest.