Last season was a nightmare for Seattle running back Shaun Alexander. The 2005 MVP broke a bone in his foot during the third game of the year and had to sit out for six weeks. He returned for the second half of the season, but despite a 201-yard game against Green Bay in Week 12, he clearly was not the same player he had been in previous years. When all was said and done, Alexander had dropped to 3.6 yards per carry and just seven touchdowns in 2006 from 5.1 yards per carry and a record-breaking 27 rushing touchdowns in 2005.

Now that he’s had a few months off to rest and recover, conventional wisdom says that Alexander will once again be one of the NFL’s elite running backs. Peter King ranked Alexander as the 36th best player in last week’s issue of Sports Illustrated, and once again Alexander is a popular pick in the first round of fantasy football drafts across America.

However, Alexander is now 30, an age when running backs generally are slowing down, not speeding back up. Even without considering age, it is rare to bounce back from the kind of decline Alexander had last year. In fact, it is rare for a running back to decline as much as Alexander did last year, period.

Since 1978, only six running backs lost more than 1.5 yards per carry off their rushing average, with a minimum 200 carries each season. Only two of these running backs were 26 or older: Alexander and Barry Sanders. Sanders dropped from 6.1 yards per carry in 1997 to 4.3 yards per carry in 1998, and then retired.

If we loosen the restrictions a bit in our search for historical comparables, we still don’t find many older backs with a drop-off to match Alexander’s fall in 2006. From 1978 through 2005, only eight running backs age 28 or older declined by more than 1 yard per carry with a minimum 150 carries each season. Sanders, Curtis Martin, and Randy McMillan never played again. James Brooks, Marion Butts, and Corey Dillon each retired after one more year. Mike Anderson and Jerome Bettis went through a period of ineffectiveness, although each eventually rebounded for at least one good season.

Alexander also scored 20 fewer touchdowns in 2006 than he did in 2005. That’s not something that happens often, primarily because very few running backs have enjoyed seasons with more than 20 touchdowns in the first place. However, a look at other veterans with dramatic scoring drops shows very little historical precedent for the belief that Alexander will return to his high-scoring ways.

Nine other running backs aged 28 or older have dropped by eight or more touchdowns compared to their average over the previous two seasons. These running backs averaged 14.0 rushing touchdowns the year before their drop, but just 4.4 touchdowns one year later, and just 3.8 touchdowns two years later. Only Emmitt Smith (1998) had more than seven touch downs two years later, and only Smith and Wendell Tyler (1984) had more than 700 rushing yards. (Tyler’s 1982 numbers are prorated due to that year’s strike.)

Fans of Alexander might argue that the Seattle running back is different, more talented or dedicated than these other running backs. But is that really true? Dillon and Martin were the top two runners in the league the year before they each declined. The list of players who saw their touchdowns disappear and never return includes Priest Holmes, who set the touchdown record which Alexander broke in 2005, as well as John Riggins, Herschel Walker, and a name familiar to Seahawks fans, Curt Warner.

Pass reception stats provide another indicator that Alexander will struggle to return to greatness. A drop in pass receptions is often a good indicator that a running back only has one or two good years left, even if the running back is still productive carrying the ball. Alexander had 59 receptions in 2002 and 42 in 2003 before dropping to 23, 15, and 12 over the past three seasons.

Alexander is one of 13 running backs, 27 or older, who had a season with at least 140 carries but fewer than 25 receptions two years after a season with at least 150 carries but more than 40 receptions. In fact, Alexander is the only player since 1978 to have two such seasons, 2004 and 2005.

What about the other 12 players on this list? Dillon, Martin, Warner, and Sanders all appear again, along with onetime 49ers great Roger Craig, who ended his career as a part-time player in Oakland and Minnesota. Six of the other seven players retired after one more season: Pete Johnson, Kevin Mack, Duce Staley, Anthony Toney, Lorenzo White, and Ricky Williams. In their final seasons — not counting Williams’s numbers in the CFL last year — these six running backs combined for just 329 carries and 1,001 rushing yards, barely three yards per carry. The final player on the list is Alexander’s contemporary, Fred Taylor of Jacksonville. Taylor has only 36 receptions over the past two seasons after catching at least 36 passes four times between 2000 and 2004, a sign that he too is approaching the end of his career.

Alexander was one of the league’s top backs from 2003 through 2005, and no amount of historical list-making can take that away from him. There is no doubt that Alexander has spent the past few months working hard, trying to rebuild that great combinationofspeedandstrength that powered his 2005 MVP season. Unfortunately for Alexander and for Seattle’s hopes of returning to the Super Bowl, the odds are stacked against him.

Mr. Schatz is the editor in chief of FootballOutsiders.com.