At the end of the day, all rushing yardage is created equal. However, the manner is which your running backs attain those totals should be monitored closely, because changes within the environment in which they run could alter their future production. One manner in which to gauge how a back churns out those yards is by looking at the number of big-play rushes that go for 20 or more yards. So far this season, there are 31 running backs who have broken at least two 20-yarders. Here they are, listed by the number of big-play rushes they have this season:
Willie Parker, Steelers: The fact that Parker is leading the NFL within this metric with eight big-play rushes shouldn't be surprising at all; the Steelers are second in the league with 159 rushing yards per game. With a stellar offensive line, one of the best blocking wide receivers in Hines Ward and an extremely favorable schedule ahead, look for Parker to remain the league leader.
Adrian Peterson, Vikings: It would seem that the only people on earth that don't want "All Day" to get more rushing attempts is the Minnesota brain trust. It would appear that the rushing game that everyone expected to materialize when Chester Taylor and Steve Hutchinson joined the Vikings has finally arrived. Despite having only 108 rushing attempts in his rookie season, Peterson is quickly becoming the favorite to be selected as the No. 2 back overall in 2008 fantasy drafts, in part because of his six carries that have gone for 20-plus yards.
Marion Barber III, Cowboys: To be honest, in my first draft of this column, my initial comments on Peterson were focused on his insane level of big-play rushes versus his limited rushing attempts. Then I moved down one slot to Marion Barber, whose five big-play rushes have come in 24 fewer attempts than Peterson. If Julius Jones were to leave the picture (because of trade, injury or benching), Barber would quickly join the ranks of the elite running backs.
Larry Johnson, Chiefs: As many predicted, there have been two LJs this season: the one who was invisible in the first few games and the one who has feasted on teams not necessarily known for their defenses. However you look at it, it seemed highly unlikely that Johnson would be tied for third with five big-play rushes at this point in the season. Many experts are advising owners to sell high on Johnson, based on his recent performances. I'm not one of them. This number indicates that the blocking in front of LJ has been sound, and he's getting to the second level of defenses. If that continues, there's no reason to expect Johnson not to remain dominant.
Justin Fargas, Raiders: We'd love to view Fargas' four big-play rushes as a sign of things to come for Fargas, but as long as LaMont Jordan is healthy, Fargas won't have the opportunities to continue to compile them.
Maurice Jones-Drew, Jaguars: It's no surprise that MJD has game-breaking ability, but considering how much of a bust he was during the first quarter of the season, the fact that he's among the league leaders in this category with four big-play rushes should ease your concerns over his prospects the rest of the season.
LaMont Jordan, Raiders: Love me the LaMont, just hate me his back problem. If you need a high-risk, high-reward player, look no further than Jordan. As long as his back remains a non-issue, he's just on the outside of the highest-rated running backs.
Jamal Lewis, Browns: Considering he has missed some games due to injury, the fact that Jamal's four big-play rushes equal the individual totals of Brian Westbrook, Shaun Alexander and LaDainian Tomlinson should be viewed as an astonishing feat. Lewis should return this weekend, and he makes for a fine No. 2 back the rest of the way.
LaDainian Tomlinson, Chargers: Tomlinson has four big-play rushes. No further analysis is needed -- he's still the best in the world.
Brian Westbrook, Eagles: It should be no secret that Westbrook's value comes via the big play. Keep an eye on tackle Jon Runyan's tailbone (seriously). Runyan fractured it in a freak injury, and his status will have a direct impact on Westbrook's productivity.
Shaun Alexander, Seahawks: Despite the fact the Seahawks haven't had a bye yet, Shaun Alexander ranks as the 20th highest-scoring running back this season. To put that in perspective, that's one slot behind LenDale White. I don't know about you, but if you go by the mantra that a bust can't be injury-related, Alexander is shaping up to be the season's biggest fantasy bust.
Willis McGahee, Ravens: McGahee has surprised me this season, grinding yardage out at a nice pace. Currently the No. 5 running back overall this season in standard ESPN.com scoring, McGahee, with three
big-play rushes, is likely to finish as a second-tier running back.
Jerious Norwood, Falcons: At some point, you have to believe that Atlanta is going to start focusing on the future. When that occurs, look for Norwood to become the featured back. If he maintains his explosive production, he'll have that job to himself next season. If he doesn't, he'll continue being a change-of-pace back. For this season, though, he's a flex option, at best.
Ronnie Brown, Dolphins: Sometimes the brightest spot on a bad team can make for an excellent play. Unfortunately, sometimes that player also tears an ACL and kills fantasy teams in the process.
Chris Brown, Titans: He's still Chris Brown, so I don't care if his two big-play rushes are as many as Reggie Bush has. There's a chance Brown will become a healthy game day inactive down the road if Chris Henry can produce like he did this past weekend.
Reggie Bush, Saints: Don't be fooled by Reggie's low yards-per-carry average or the fact that he has only two big-play rushes. His game-breaking ability is featured in the Saints' passing game, and with six catches per game, he's on pace to exceed last season's total of 88 receptions.
Jesse Chatman, Dolphins: In limited action, Chatman has displayed explosiveness worthy of fantasy consideration. Now he's being handed the starting gig after Ronnie Brown torn his ACL. Chatman makes for a fantastic flex option the rest of the way.
Najeh Davenport, Steelers: Davenport's two big plays should be discounted when calculating his true fantasy value. He's a touchdown vulture and nothing more.
Frank Gore, 49ers: If your team is scoring just 13.0 points per game, you know big plays aren't exactly happening on offense. Last season, Gore led the league with 15 rushes for 20 yards or more. Not much has changed
on the 49ers' offense, so look for those big runs to return sooner rather than later.
Earnest Graham, Buccaneers: Whoever in your league won the Earnest Graham free agent sweepstakes has a player who will remain a yardage beast for as long as Michael Pittman remains out. Pay no attention to the trade for Michael Bennett. Every smart team takes out an insurance policy against a complete collapse. Bennett is just that.
Henry, Broncos: If you own him, you start him as long as he's playing. Which, of course, could be only two more weeks if he's suspended prior to Week 10.
Brandon Jacobs, Giants: The Giants' offensive line has been the best in the league this season. I say that as a Patriots fan and having watched every minute of both teams' games. Jacobs has completely changed my opinion of him; I'd be quite satisfied to have him as my second running back.
Edgerrin James, Cardinals: James has defined the term workhorse this season, having carried the ball 156 times already. That's a pace of 357 carries for the season. Even if he gains 3.0 yards per carry, that's almost 1,100 rushing yards alone.
Julius Jones, Cowboys: When you're supposed to be the speed guy in a time share, it's never good to have only two big plays compared to your partner's five. I used to be a Jones apologist. Not anymore.
Kenton Keith, Colts: Surprised to find Keith here with no sign of Joseph Addai? Keith has become an absolutely needed handcuff to Addai and could put up No. 1 back numbers in the event of an Addai injury.
Marshawn Lynch, Bills: Lynch is almost the whole Bills offense, and he's doing it by being an absolute workhorse. When you compare his two big-play rushes versus his 127 rushing attempts, you can see that his value is in the number of touches he receives and not in his big-play ability.
Fred Taylor, Jaguars: Old man Taylor still gets it done. It's hard to believe that a running back with a reputation for being fragile is actually doing well in his 10th NFL season. When you factor in Jones-Drew's production with Taylor's, it's clear the Jacksonville running scheme is conducive to big plays.
Michael Turner, Chargers: Last season, Turner received many carries in mop-up duty for Tomlinson. This season, the Chargers are in a dogfight for the division title and aren't dominating teams like they did last season. The residual effect is that Turner is worth nothing more than a handcuff at this point.
DeShawn Wynn, Packers: Say what you want about how bad the Packers' running game is, but Wynn's two big-play rushes are still more than anyone from the Patriots, Jets, Redskins or Panthers has.
Selvin Young, Broncos: Travis Henry's appeal of his alleged violation of the league's substance abuse program likely won't be heard until just after the Week 9 games. However, his recent injury opens a potential opportunity for Young to become a fantasy factor in the very near future.
Ken Daube is a fantasy football analyst for espn.com.