The danger of ranking running backs in August was made perfectly clear last Thursday, when we learned Browns rookie Trent Richardson would have knee surgery.

Later that night, the Chargers' Ryan Mathews fractured his clavicle in San Diego's preseason opener and is expected to miss 4 to 6 weeks.

You could say we've made some changes to these rankings.

Some notable updates from the running back rankings we posted Aug. 8 (the above link reflects our current rankings):

-- Chargers coach Norv Turner said Mathews' injury is "not so bad." I can only hope. In a keeper league in which I participate, I traded for Mathews prior to training camp and now must decide if he will still be one of my three keepers (probably).

The Chargers open the season Monday, Sept. 10 at Oakland --  31 days after Mathews' surgery. The guess here is Mathews will return in Week 2 against Tennessee, and considering the lack of studs at the position, I think he remains a top-10 player at the position.

Yes, injuries are a concern -- Mathews has played 26 games in two years. But consider this: Last season, he averaged 4.9 yards per carry and caught 50 passes. In 14 games, he racked up 1,546 total yards.

Would you rather have Mathews coming off a shoulder injury or Adrian Peterson following an ACL tear.

I'll take Mathews.

-- Richardson, who is expected to start the Browns' opener against the Eagles, dropped from No. 14 to 17.

-- The (expected) uncertainty of the backfield situation in Washington -- Mike Shanahan, tormenting fantasy owners since 1995 -- has resulted in Roy Helu dropping from No. 24 to 29 at running back. Redskins teammate Evan Royster, who could be Washington's featured back (your guess is as good as mine when it comes to Shanahan), went from unranked in the top 50 to No. 41. Another Redskin, the (always) beat-up Tim Hightower, dropped from No. 41 to out of the rankings.

-- Ronnie Brown, who would start the season opener for the Chargers if Mathews can't go, is in the top 50 at No. 47. Don't get too excited about Brown, who averaged 3.2 yards per carry in a limited role for the Eagles last season.

Once the unquestioned king of fantasy football positions, the 2012 crop of running backs has three hammers -- Arian Foster, Ray Rice and LeSean McCoy -- then a lot of questions.

-- Will Maurice Jones-Drew's holdout end before your draft?

-- Where do you draft former no-doubt-about-it No. 1 overall fantasy pick Adrian Peterson, who is recovering from a torn ACL?

-- Can you trust Chris Johnson after last year's holdout/four-TDs-in-16-games debacle?

-- Is the injury-prone Ryan Mathews going to be as good as everyone seems to think he will be now that goal-line vulture Mike Tolbert has left town?

-- Will Matt Forte be as good now that Michael Bush could serve as the Bears' goal-line vulture?

-- Can Darren McFadden stay healthy?

-- Should you be concerned that Trent Richardson is already banged up?

-- Can DeMarco Murray sustain his 2011 rookie success over a full season?

You get the idea.

On to our second set of rankings for 2012, which reflects updates we made Aug. 12:

Rank, player, team (bye week): GP, Rushing yards-Avg-TD, Receptions-Yards-TD
1. Arian Foster, Hou (8): 13, 1,224-4.4-10, 53-617-2

2. Ray Rice, Bal (8): 16, 1,364-4.7-12, 76-704-3

3. LeSean McCoy, Phi (7): 15, 1,309-4.8-17, 48-315-3

4. Maurice Jones-Drew, Jac (6): 16, 1,606-4.7-8, 43-374-3

5. Chris Johnson, Ten (11): 16, 1,047-4.0-4, 57-418-0

6. Matt Forte, Chi (6): 12, 997-4.9-3, 52-490-1

7. Darren McFadden, Oak (5): 7, 614-5.4-4, 19-154-1

8. DeMarco Murray, Dal (5): 13, 897-5.5-2, 26-183-0

9. Steven Jackson, StL (9): 15, 1,145-4.4-5, 42-333-1

10. Ryan Mathews, SD (7): 14, 1,091-4.9-6, 50-455-0

11. Adrian Peterson, Min (11): 12, 970-4.7-12, 18-139-1

12. Marshawn Lynch, Sea (11): 15, 1,204-4.2-12, 28-212-1

13. Fred Jackson, Buf (8): 10, 934-5.5-6, 39-442-0

14. Michael Turner, Atl (7): 16, 1,340-4.5-11, 17-168-0

15. Frank Gore, SF (9): 16, 1,211-4.3-8, 17-114-0

16. Jamaal Charles, KC (7): 2, 83-6.9-0, 5-9-1

17. Trent Richardson, Cle (10): Rookie

18. Darren Sproles, NO (6): 16, 603-6.9-2, 86-710-7

19. Shonn Greene, NYJ (9): 16, 1,054-4.2-6, 30-211-0

20. Ahmad Bradshaw, NYG (11): 12, 659-3.9-9, 34-267-2

21. Reggie Bush, Mia (7): 15, 1,086-5.0-6, 43-296-1

22. Isaac Redman, Pit (4): 16, 479-4.4-3, 18-78-0

23. Willis McGahee, Den (7): 15, 1,199-4.8-4, 12-51-1

24. BenJarvus Green-Ellis, Cin (8): 16, 667-3.7-11, 9-159-0

25. Doug Martin, TB (5): Rookie

26. Stevan Ridley, NE (9): 16, 421-5.1-1, 3-13-0

27. Jonathan Stewart, Car (6): 16, 761-5.4-4, 47-413-1

28. Beanie Wells, Ari (10): 14, 1,047-4.3-10, 10-52-0

29. Roy Helu, Was (10): 15, 640-4.2-2, 49-379-1

30. DeAngelo Williams, Car (6): 16, 836-5.4-7, 16-135-0

31. Ben Tate, Hou (8): 15, 942-5.4-4, 13-98-0

32. Donald Brown, Ind (4): 16, 645-4.8-5, 16-86-0

33. Peyton Hillis, KC (7): 10, 587-3.6-3, 22-130-0

34. C.J. Spiller, Buf (8): 16, 561-5.2-4, 39-269-2

35. Toby Gerhart, Min (11): 16, 531-4.9-1, 23-190-3

36. Mark Ingram, NO (6): 10, 474-3.9-5, 11-46-0

37. James Starks, GB (10): 13, 578-4.3-1, 29-216-0

38. Kevin Smith, Det (5): 7, 356-4.9-4, 22-179-3

39. Felix Jones, Dal (5): 12, 575-4.5-1, 33-221-0

40. Michael Bush, Chi (6): 16, 997-3.8-7, 37-418-1

41. Evan Royster, Was (10): 6, 328-5.9-0, 9-68-0

42. Daniel Thomas, Mia (7): 13, 581-3.5-0, 12-72-1

43. LeGarrette Blount, TB (5): 14, 781-4.2-5, 15-148-0

44. Jahvid Best, Det (5): 6, 390-4.6-2, 27-287-1

45. David Wilson, NYG (11): Rookie

46. Ryan Williams, Ari (10): Didn't play
47. Ronnie Brown, SD (7): 16, 136-3.2-1, 0-0-0

48. Mike Goodson, Oak (5): 16, 452-4.4-3, 1-4-0

49. Shane Vereen, NE (9): 5, 57-3.8-1, 0-0-0

50. Bernard Scott, Cin (8): 16, 380-3.4-3, 13-38-0

NOTE: All statistics are from the 2011 season.

QUICK SLANTS: In the last two seasons, Foster has rushed for 2,840 rush yards, caught 119 passes for 1,221 yards and scored 30 total TDs in 29 games. … Rice’s 15 TDs in 2011 were one more than he had combined in otherwise productive 2010 and ’09 seasons. … McCoy’s TDs were way up (from nine in 2010 to 20 last season), and his receiving numbers were significantly down (from 78 catches for 592 yards in 2010). … Jones-Drew had 30 total TDs in 2008 and ’09, but has averaged nine TDs in the last two years. … In 2009 and ’10, Johnson had 28 total TDs. … The Rams' Jackson has 60 total TDs in 115 career games, and 16 were in 2006. … Lynch had 24 TDs in his first five NFL seasons. … McFadden has missed 19 games in four years. … Turner has 50 rushing TDs in 59 games in four seasons with the Falcons. … Gore had 13 TDs in 14 games in 2009. He has 39 total TDs in the other 86 contests in which he has played in his career. ... Reggie Bush had never run for more than 581 yards in his first five NFL seasons. … In the last two games of the Steelers' 2011 season, including a postseason loss at Denver, Redman had 213 yards rushing, one TD and five catches for 39 yards. … Green-Ellis has 24 TDs the last two years. … The Panthers' Stewart had 21 TDs in his first two seasons and has eight in the last two. … DeAngelo Williams had 20 TDs in 16 contests in 2008. He has 22 total TDs in the other 64 games in which he has played. … Hillis had 13 total TDs, 1,654 total yards and 61 catches with the Browns in 2010.

PREVIOUS RANKINGS: Quarterbacks

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START

Raiders: RB Michael Bush, K Sebastian Janikowski

Chargers: QB Philip Rivers, RB Ryan Mathews, RB Mike Tolbert, WR Vincent Jackson, TE Antonio Gates, K Nick Novak

Quick slants: With Darren McFadden out with a foot injury, Bush will be the Raiders' featured back. He ran for 96 yards on 19 carries and caught two passes for 33 yards and a touchdown last week. ... Janikowski has made 13 of 14 field-goal attempts, is perfect on 19 PATs and has 58 points in seven games. ... Rivers has been disappointing (11 TD passes and 14 interceptions), but he's thrown for 2,469 yards, including 754 in his last two. He had four TD passes and three interceptions last week against the defensively challenged Packers. ... Mathews is expected to play after missing last week with a groin injury. He has rushed for 509 yards and has 30 catches for 342 yards in seven games. He hasn't scored a touchdown in his last four games. ... Even if Mathews starts tonight, Tolbert should get about 15 touches. He has six TDs on the year and has reached the end zone twice in his last two contests. ... Jackson had seven receptions for 141 yards and three TDs last week. ... In three games since returning from a foot injury, Gates has 17 receptions for 223 yards and two scores. He had eight catches for 96 yards and a TD on Sunday. ... Novak has been prolific in place of the injured Nate Kaeding, making 16 of 17 field goals and all 17 of his PATs. He is averaging 9.3 points per game.

SIT

Raiders: QB Carson Palmer, WR Darrius Heyward-Bey, WR Jacoby Ford, defense/special teams

Chargers: WR Malcom Floyd, defense/special teams

Quick slants: Palmer has thrown six interceptions in two games with the Raiders. ... Heyward-Bey has been productive, but he was shut out last week, and the Raiders' passing attack is too unreliable. ... Ford had five receptions for 105 yards and a TD last week, but he had only 11 catches for 114 yards and zero TDs prior to his breakout game. ... The Raiders' defense ranks 27th in yards allowed per game (386.5) and 30th in points allowed (27.0). ... Floyd is expected to sit tonight because of a hip injury. If he's active, I'd keep him on my bench. ... The Chargers' defense ranks seventh in yards allowed (311.6), but is 27th in points (25.5), tied for 20th in sacks (17) and has forced only 11 turnovers.

Steven Jackson has missed practice this week with a groin injury.

Those surprised, raise your hand. If you selected Jackson among the top four picks, scared off by Maurice Jones-Drew's preseason injury or Ray Rice's ability to sustain his production, you might be pounding your head on your desk or repeatedly yelling "Frank Gore!" instead of raising said your arm.

"The leg's still tight, the groin's still tight, so it's just one of those injuries where just time is what's really going to heal the injury," Jackson told reporters Thursday.

Just a guess: He's not playing this week.

Jackson missed four games in both 2007 and '08, and in the 42 games he's played since 2007, he has a mediocre total of 19 touchdowns.

Sunday's opponent, the Seahawks, rank fifth against the run and are allowing only 2.6 yards per carry.

If Jackson is active, you have to play him. If he's out, backup Kenneth Darby -- who had 14 carries for 49 yards and one TD last week -- should get most of the work, since No. 3 back Keith Toston is also nicked up.

If Jackson is inactive, Darby is a decent flex play in PPR formats. He had a combined 37 receptions in 2008 and '09.

Jackson might be resting up for Oct. 10. In Week 5, the Rams will play at Detroit, the league's worst run defense.

Let's look at four more running backs who have had injury issues (note: We'll address Ray Rice's knee bruise in a column for Friday's print and online editions):

-- Chargers rookie Ryan Mathews returned to practice after sitting last week because of an ankle injury. If he plays Sunday against Arizona, as he should, he should be in your lineup. The Cardinals rank 31st against the run and are allowing 146.3 yards rushing per game.

-- Clinton Portis, who shared carries with Ryan Torain last week because the former has a wrist ailment, seems to be a go for Week 4. Sunday's opponent, the Eagles, have struggled against the run (No. 23, 128.7 yards per game, three touchdowns). Portis is a low-level No. 2 back at best, though, after rushing for all of 634 yards in 11 games since the start of last season.

-- The Broncos haven't ruled Knowshon Moreno out, but he isn't practicing because of a hamstring injury and seems certain to miss Sunday's game at Tennessee. If Moreno is out, Laurence Maroney is a better play than Correll Buckhalter, but neither is a top-25 back this week.

-- Just when it seemed Pierre Thomas had the Saints' rushing workload to himself, he injured his ankle last week and will be a game-time decision Sunday against Carolina. If Thomas sits, rookie Chris Ivory, who had seven carries for 13 yards last week, is a flex play vs. the Panthers (No. 14 vs. the run).

Stat of the week

8.5: Chiefs running back Jamaal Charles' average yards per touch this season. He has 34 carries for 238 yards and one touchdown, and five catches for 92 yards. Meanwhile, starter Thomas Jones, who has 18 more carries than Charles, is averaging 4.1 yards on 54 touches.

The Chiefs are 3-0, so obviously it's working. But the fantasy geek in many of us wonders if Todd Haley and Charlie Weis have forgotten that Charles held up just fine with an increased amount of touches in the second half of 2009.

Programming note: Check back late Thursday night or Friday morning for a column in the N-H's online Sports section that will break down five of the most disappointing players from a fantasy perspective in the first three weeks.

Prior to the season, the last four words of the headline above would have seemed about as likely as Shonn Greene getting outplayed by LaDainian Tomlinson, Jamaal Charles getting 11 carries per game, John Kuhn being a factor in Green Bay's featured back equation and Felix Jones and C.J. Spiller being less exciting than the WB's prime-time lineup.

Wait, all of that has happened? Let's just move on.

Tolbert, a 5-foot-9, 243-pound fullback and special-teamer in his first two seasons with the Chargers, might be the featured back Sunday at Seattle.

Rookie Ryan Mathews was limited to five carries last week because of a high ankle sprain, and he's missed practice this week because of the ailment. Thursday, NFL.com reported it was unlikely he would play against the Seahawks.

Enter Tolbert, who had 16 carries for 82 yards and two touchdowns in Week 2 -- pretty impressive for a back who had 38 rushing attempts in 29 games in his first two NFL seasons.

The Seahawks rank fifth against the run, but since Tolbert, and not Darren Sproles, should get the goal-line carries, I'd consider the former a No. 2 fantasy back this week.

Sproles is most effective in point-per-reception leagues. He had 45 catches, compared to 93 rushing attempts, last season. In Week 2, even with Mathews missing most of the game, he had only five rushing attempts, but piled up 100 total yards (37 rushing, 63 receiving) and caught four passes.

Sproles is a decent flex play in deeper leagues this week if Mathews sits.

As for Tolbert, should Mathews miss more than one game, San Diego's schedule is very favorable in Weeks 4, 5 and 6. The opponents -- the Cardinals, Raiders and Rams -- rank 31st, 29th and 30th, respectively, against the run this season.

I believe in Mike.

In our News-Herald PPR league, six of the top seven backs thus far are Jahvid Best, Arian Foster, Matt Forte, LeSean McCoy, Darren McFadden and Jason Snelling.

Tolbert should fit right in.