You may have seen that Larry Johnson was released by Washington last week, and there are rumors that he might be signed as a quick fix in St. Louis now.Larry Johnson was one of the greatest running backs I ever saw. That was mainly the end of 2004 and all of 2005. In 2005, he ran 1,750 yards and 20 touchdowns. He had a great offensive line blocking, but he was still a force of nature, a near unstoppable blend of power and speed. I wrote at the time that he was awfully similar to the great Jim Brown, and I actually heard from two of Brown’s former teammates, who agreed.Now, five years later, he’s out of a job. No doubt Larry brought some of his pain on himself with the way he lived his life. He has made his share of mistakes — on the town, on Twitter, etc.But I wonder how much his career was bludgeoned by the little fact that that in 2006, the Chiefs ran Johnson an NFL record 416 times. I wrote at the time that backs who were used THAT MUCH tended to fade quickly. Look at the backs who have gotten 400 carries in an NFL season.1. Larry Johnson, 416, 2005– Never again gained even 900 yards, was released less than three years later.2. Jamal Anderson, 410, 1998– Started only two games the next year. In 2000, he ran for 1,024 yards and a blah 3.6 yards per carry. After three more games, he retired.3. James Wilder, 407, 1984– Wilder did carry the ball another 365 times the next year; he was some kind of resilient (though not especially effecting — 3.8 yards per carry in 1984, 3.6 in 1985). But after that his rushing yards dropped to 704 to 488 to 343 to 244.4. Eric Dickerson, 404, 1986– An exception to the rule … sort of. Four times in Dickerson’s career, he ran the ball 375 times or more. Only one other back has done it more than once — go ahead and guess. Dickerson still had one more great season, and a couple more good seasons after ;his 400-carry campaign.5. Eddie George, 403, 2000.– George was never a big yards-per-gain kind of back. But after his 400-carry season, he averaged 3.3 yards per carry for the rest of his career.Running backs, it seems to me, only have so many carries in them. The burst that makes a great running back is slowed just a tiny little bit with every carry — like sands in the hour glass.* There are some who have more sand in their hourglass. Emmitt Smith led the league in carries three times — he was a freak (but he was also a different back after he turned 27 than he was before). Walter Payton led the league in carries four years in a row and was still a great older back. Jim Brown led the league in carries six years, and never relented.*So are the Days of Our Lives.But it’s also true that none of them carried the ball 400 times in a regular season. Jim Brown only once carries the ball 300 times. Larry Johnson never looked the same to me after 2005. His line did deteriorate, as did the team around him. And his head was clearly clouded — there was a holdout in there too. Still … I tend to think all those carries took their toll.The only other player besides Eric Dickerson to get 375-plus carries in a season more than once is … Ricky Williams. I wouldn’t have guessed that. He had 383 and 392 carries in back-to-back seasons. The first season, it should be noted, he averaged 4.8 yards per carry. The second, he averaged 3.5.