2009 Draft Prep: Breaking down RB breakdowns

We don't mean to give you disappointing news, but turning 30 years old has absolutely nothing to do with when a running back breaks down. It's not like a rusher is healthy as a horse the day before his 30th birthday and then can't get out of bed the next day.

There is no curse, no jinx and no truth to the rumor that life ends at 30 -- which is good for us 33-year-old Fantasy writers.

The new numbers you need to remember for figuring out when a running back might decline are eight and 2,500.

Eight: The amount of full seasons a running back takes on.

2,500: The amount of carries a running back has in his career, including postseason.

Now when we talk about a "full season," we mean a consistent workload over the course of a year. There's no set number of touches that can really determine this, but you can make the assumption that we're not talking about 200 carries. But we do consider two seasons of doing a decent amount of work as one full season.

And when we discuss 2,500 carries, the same logic applies to that as the 30-year-old analogy we made above: Don't expect a running back to be healthy as a horse on career carry 2,499 and then keel over on 2,500. It's more of a rounded number between a range where a running back might start slowing down.

There's another factor: Injuries. This isn't something that can be measured with a number. Players who suffer a major injury or a series of minor injuries will almost always struggle to maintain the level of play they were at before getting hurt. Many running backs' careers have been shortened by torn ACLs and the like. When rushers miss time with serious lower-body injuries, their career clocks tick even faster, so much so that the aforementioned factors might not even apply.

What constitutes a breakdown?

There is a statistic that can reliably tell when a running back isn't as consistent as he once was: Average per carry. Touchdowns aren't a fair indicator because they're essentially random, and total yards are part of the end result of the rushing average. Typically, anyone at or higher than 4.0 yards per carry is doing a good job. That's a regularly accepted number by football evaluators. As long as a running back is maintaining that average while posting full seasons, there's not much to worry about, at least until he begins to creep up into a high total of career carries. Clearly, when a running back's average begins to tank, you can raise your eyebrows.

Consider these prominent NFL running backs from the last 15 years. Our breakdown theory would apply to them since running backs never got to 300 carries in the NFL's formative years. And, as you'll see, they all disprove the idea that running backs decline at 30 years of age.

Check out how many full seasons of work most of these running backs had before their breakdown. And when they did finally break down, they either walked away from the game or faltered -- check their stats and see for yourself. When you see that rushing average decline, you know something is not right.

Who's next?

With our red flags defined, let's see who in the NFL might be a candidate to underperform this season. This is strictly a table based on our criteria and not a prediction of doom for these players.

Name	Age as of Week 1	Major injury	Eight-plus seasons	Near/Over 2,500 carries
Ladell Betts	30
Correll Buckhalter	30
Kevin Faulk	33
Edgerrin James	31
Thomas Jones	31
LaMont Jordan	31
Jamal Lewis	30
Sammy Morris	32
Dominic Rhodes	30
Fred Taylor	33
LaDainian Tomlinson	30
Brian Westbrook	30
Ricky Williams	32

Here's the interesting thing about this list -- every single player listed above is either a backup or will receive help running the ball this season. The Chargers kept Darren Sproles to aid Tomlinson; the Eagles drafted LeSean McCoy as a backup to Westbrook; Taylor, Morris and Faulk are all sharing the rushing duties in New England; and Lewis and Jones might have two other backs -- one of each of them being a rookie -- pitching in throughout 2009.

There's good news and bad news regarding the future of running backs in the NFL: With teams relying on tandems and committees to get the run game going, fewer players will even have the chance to meet the red flags from our research. The days of 300-carry running backs lasting years and years are coming to an end, partially because of research like this and partially because there's just too many good running backs out there. But because of this, the running backs we'll come to know and love over the next several years should be able to last longer -- possibly beyond their 31st and even 32nd birthdays -- because their bodies will be in shape and not damaged from being in the equivalent of a car accident 25 times a week.

And anything that extends the careers of great NFL running backs is good for Fantasy Football.

Have a question or a comment for Dave about Fantasy Football? Send your thoughts or questions to DMFantasyFootball@cbs.com and he'll get to as many as he can. Be sure to put Attn: RB Research in the subject field. Include your full name, hometown and state.