One of the most valuable articles in Pro Football Prospectus 2008 describes a new way to predict the future performance of rookie running backs.

In “Five Seconds Can Be a Lifetime,” Bill Barnwell describes a simple equation that combines a rookie’s weight and 40-yard dash time into one number that is better than any other number in predicting if that running back will be a success in the NFL.

He calls that number the Speed Score and calculates it with this equation:

The faster a player’s time, the higher the Speed Score. Also, if two players run the exact same 40 time, the one that is heavier gets a higher score because he had to run the time with more weight on his body.

When Barnwell looked at past rookies and how they later performed, he found that many successes had a speed score greater than 100 and many busts had speed scores less than 100.

I don’t want to give away too much, but when you look at the list of players it picked to succeed versus those it didn’t is pretty impressive. It is slightly biased because a 40-yard dash time that isn’t weight adjusted is already a good indicator of success. However, their statistics show that the speed score is slightly better than the 40-time alone.

Can you guess which rookie this year posted the highest speed score at the combine? You’ll have to buy the book to find out, but I will say that it wasn’t McFadden.

For the past eight years, it has been expected that you could draft at least one 300-carry running back for your fantasy team. That’s because there have been approximately ten 300-carry running backs each year since 2000.

Except for last year. In 2007, only six running backs hit the 300-carry mark. A huge drop-off from previous years.

Those lost offensive opportunities shifted to the passing game. In 2007, there were eleven wide receivers with 90 or more receptions, up from seven the previous year.

Below is a graph showing the trend of highly-used wide receivers and running backs since 2000 (Data from Pro-Football-Reference).

These stats probably aren’t a surprise to most fantasy owners. Everyone knows that last year was a huge passing year in the NFL.

I was surprised, however, by the fact that wide receivers have never had such an advantage over running backs. Even in the early 2000s, wide receivers only held a one-player advantage.

Another interesting fact is that these two lines don’t cross frequently. The last time there was a shift from wide receivers to running backs in 2003, there were four solid years of running backs out-performing wide receivers.

Was last year a fluke or the start of a new trend? My guess is that this is a new trend that fantasy owners will need to keep in mind when drafting this year.

Most fantasy football articles are reports and analysis about current events. A month later, though, no one really cares how Steven Jackson’s groin was on October 3rd.

That’s why Doug Drinen’s archive of fantasy football ramblings is so interesting to read. He wrote a series of articles before the 2002 season, and a lot of them contain nuggets of fantasy information still useful today.

If you haven’t had a chance to read them, check out the main page first before heading over to the full list.

A couple highlights:

The best wide receiver of a rookie class is practically never the best career receiver.

The best running back of a rookie class is almost always the best career back.

If I have time I’ll try to do my own update on some of his articles, but I wanted to first share his archive with anyone not familiar with it. I know in one of the articles he studies the third-year wide receiver breakout theory, but I can’t remember which one.

Start browsing now. It’s a great way to kill time. To keep it interesting, some of the articles are entirely opinion like the Randy Moss and Jake Plummer ramblings.

I mentioned last week that I’m a fan of Pro Football Prospectus, and this year’s edition is definitely worthwhile.

One article that I find interesting is the study of how a wide receiver’s height and BMI can be an indicator of success.

The way they predict success is by determining whether or not a player falls into one of four sections on a chart of height versus BMI. The study pooled data from the past ten years and compared players by looking at average yards per game.

Here is a rough sketch of their complete graph with some representative players shown:

The theory is that if a player falls into one of the four boxes, they have a decent chance of being a top wide receiver. Conversely, if a player doesn’t have a body type that fits into one of the four boxes, then they have only a small chance of being an elite receiver.

If you’re wondering how big these relative differences in body type are, below I added myself for comparison. At 6′ 2″ and 170 lbs, I fall just a bit on the light side of a successful NFL wide receiver:

This article is by far the most extensive study I’ve seen on how well body type can predict success. I am a little hesitant at the moment to take the results as fact though.

The main reason is that I don’t think there is enough data to justify drawing four separate zones on this graph. The theory is probably overfitting the data. For example, the height difference between the top and bottom zones is only two inches.

Second, I’m not convinced there is a legitimate football-related reason why these narrow zones of body type would be successful and others wouldn’t. Especially that dead zone in the middle. Is there a reason why a player with that height/BMI combination is less likely to be successful?

The article suggests that the reason for these zones is that they identify which body types are able to get separation from cornerbacks and which are useful as large targets for a quarterback. They also propose that looking at the body types of defensive backs could help determine if these wide receiver body types create favorable mismatches.

Although I’m skeptical, I’m always on the lookout for hidden trends and new ways to predict successful players. I’m going to watch this one for the next few years to see if these body type trends continue.

If a new successful player emerges with a body type that is right in the middle of those four zones, I think this theory is busted. If not, and the trends continue, this could be a real way to predict success within a group of players that is usually just a crap shoot.

If anyone is interested in fantasy football auctions, FantasyAuctioneer has written an article about recent auction values of players. He notes that Randy Moss and Tom Brady have lower values in auctions than they do in drafts. Interesting read, especially if you’re doing an auction this year.

I received my copy of Pro Football Prospectus 2008 this week, and I’m excited.  I’ve read it for the past three years and it’s packed with lots of great analysis.  Being a numbers guy, this book hits the sweet spot for me.

If you’re not familiar with it, half the book is analysis and projections for NFL teams, and then the other half is projections for individual players.  They also compile projected fantasy points for each player and rank them by VBD at the end of the book.

The player projections are good because in general they are modest for almost everyone.  It helps me keep a level head when I’m really positive about a player and might draft him too early.  Their trends usually show players that have great years regress to the mean the next.

One player that they project to do well is Aaron Rodgers (if he gets a chance to play that is).  However,  I still remember a few years ago when they projected Kevin Jones and Julius Jones to be #1 and #2 in rushing yards.   Whoops!  I’ll let that one slide even though I took Kevin Jones in most of my leagues that year because of their advice.

Despite the occasional bad projection, it’s still a good book for fantasy football fans and especially those who like to analyze statistics.  I’ll try to write more about the book once I’ve finished it.  At over 500 pages, I know there’s plenty of material to cover.