Taylor struggling to produce

Jaguars running back Fred Taylor is on pace to rush for just 634 yards this season. Matthew Emmons/USPresswire

Great running backs can lose it seemingly without warning. Curtis Martin led the league in rushing in 2004 and was finished before the end of the 2005 season. Terrell Davis ran for 2,008 yards in 1998 and had only 1,194 yards over his final three, injury-filled seasons. Shaun Alexander was the NFL MVP in 2005 and was released two years later.

Jaguars veteran Fred Taylor may soon join that list. Despite being preserved from overwork by sharing time in the backfield with Maurice Jones-Drew, Taylor has taken a huge step backward this season. After running for 1,202 yards in 2007, Taylor's on pace for 634 this year -- barely half that total. While some of the backs we mentioned above can blame poor health as their excuse, Taylor noted in an interview with the Orlando Sentinel that he's healthy:

"This is the worst my numbers have been, being that I'm still healthy. In the past, I've had bad seasons because I missed 'x' amount of games. But this is the worst production that I've put out. ... It's a production business."

No doubt that it is, but why is Taylor's production down when Jones-Drew's is around the same? And more importantly, do the results of this season signify that Taylor's done?

One of the things that we do when charting the career paths of players is to use a measure known as similarity scores. The idea is to take a player's recent history, experience in the league and other factors and compare them to the same factors for other players throughout history to try and find the most similar players. It's not a perfect indicator by any means, but it's a good starting point when trying to map out a player's future.

When we take the 2007 version of Fred Taylor and compare it to the seasons enjoyed by the 10 most similar backs in history, the player who comes out as the most similar to Taylor is James Brooks, the longtime Bengals running back in Cincinnati's glory days of the late 1980s. Most interestingly, the system throws out two different Brooks seasons as the closest comparisons: 1989 and 1990. He gained over 1,000 yards in both seasons, but by 1991, he was done. Brooks saw his yards per carry drop from 5.1 (1990) to 3.8 (1991), and he was out of the league a year later.

Taylor's seen a similar drop in yards per carry this year, going from a 5.39 average in 2007 to 3.60 in 2008, a fall of 1.79. Since 1978, only one running back with at least 150 carries for the same team in back-to-back years has seen his yards per run drop more than that: Craig James, who averaged 4.67 yards for the 1985 Patriots and then 2.77 for the 1986 team. He had just eight more carries the rest of his career. The second-biggest fall? Barry Sanders, who retired after the big drop. Of the 10 players with the biggest single-season drops in yards per carry, only two recovered to approach their previous level of performance: Jerome Bettis and Warrick Dunn. While such a drop in a player's yards per carry is certainly a negative indicator of future performance, those two backs show that it's not a death knell.

While Jones-Drew has seen his average drop by only 0.34 yards, the fact that both he and Taylor have seen a decrease in performance has a lot to do with another factor -- injuries, specifically to their offensive line. Already this year, the Jaguars have lost starters Brad Meester and Maurice Williams, while key reserves Chris Naeole and Vince Manuwai have been lost for the season. Using our adjusted games lost (AGL) statistic, which takes into account the injury report, the likelihood and results of players participating, and the nature of that player's role on the team, the Jaguars have had the most injured starting offensive line in football through the first 12 weeks of the season.

If we look back to 2000, the first year we have AGL data for, the 25 teams with the most-injured starting offensive lines saw their yards per carry drop by 0.22 yards from the previous season. In the year following that injury-riddled campaign, those 25 teams experienced an improvement of 0.12 yards per carry, on average. In other words, the Jaguars should expect a slight boost when their offensive line returns to health, but not anything to correspond with the significant drop in performance that Taylor has experienced.

It's certainly not a fact that Taylor's career as an upper-echelon NFL running back is over. Taylor has hinted at chemistry issues in the media, and it's always possible that he could go somewhere else and experience a second life, a la Corey Dillon and the Patriots in 2004. When you consider the evidence, however, the preponderance of the data says Taylor's not going to recover.

Bill Barnwell is an analyst for FootballOutsiders.com.