Clearly, running back Emmitt Smith has earned the respect of his peers as the NFL's career rushing leader. “Emmitt is the greatest runner the world has ever known,” Pro Bowl defensive tackle Warren Sapp said.

We know, of course, that Sapp often speaks first and thinks later, so although we admire his loyalty to a contemporary, we beg to differ with the boastful star. Smith is retiring Thursday as the leading rusher in NFL history, but NBCSports.com doesn’t believe he is the No. 1 running back of all time.

Nor do we believe Walter Payton is No. 1 in that subjective category, either, though we agree with Smith’s comments on the late Chicago Bears’ running back. “He is a person that I looked up to and admired. He is loved by everyone,” Smith said.

Sentiment aside, there is more to being the “best” than merely compiling impressive statistics. Here is NBCSports.com’s ranking of the top 10 running backs of all-time.

1. Jim Brown (1957-65)
There has been a busload of bigger backs and a fleet of faster ones. A select group has been stronger. Seven have gained more career yards. But none was the total package that defined the Cleveland Browns’ superstar. The team wasn’t named for him, but it might as well have been. Former NFL coach George Allen once said Brown “was not only the greatest running back of all time, but one of the four or five finest professional football players of all time. He was a very big, very fast guy who combined size and speed, strength and speed, power and elusiveness better than any other runner pro football has ever had. He was a fullback who played halfback.”

Brown never missed a game in his nine seasons, earning Pro Bowl honors every year. He rushed for at least 1,000 yards seven times, fell 4 yards short once, and led the league in rushing eight times. He did it all while playing in the era of 12- and 14-game seasons. He set the NFL single-season record of 1,863 yards, in the 14-game 1963 season, when he averaged a remarkable 6.4 yards per carry. He led the league in rushing touchdowns a record five times in his career.

Noteworthy stat: Brown’s career average of 5.2 yards per carry is the highest in NFL history for any back with 750 or more carries. Imagine if he played 13 seasons like Payton and Smith.

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