Fantasy Football: Learn How to Predict Running Backs’ Yards-Per-Carry
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– Jonathan Bales
If you missed it (which is likely since we have yet to talk about it), we recently launched our 2010 Fantasy Football Package. It is a collection of everything I use to dominate fantasy football leagues each year, including my personal projections, rankings, draft plans, players to target, and so on. You can read more about the service by following the link above.
I understand it is a risk to take another person’s advice on a subject as serious (<— is that a joke?) as fantasy football, so I think it is important to detail the methodologies I implement to arrive at my final projections.
In my bio on this site, I wrote:
I have always been fascinated by the way mathematics and statistics, if used properly, can thoroughly explain seemingly complex phenomena. Like the motion of the planets or the path of an ant, I truly believe football can be perfectly represented by numbers (the difficult part is determining which numbers are significant and why). . .I implemented the same sort of approach to playing (and winning) fantasy football. Fantasy football is nothing more than risk analysis; like playing the stock market, a sound use of game theory can work wonders for your team.
This particular article is a sample of how I implement statistical analysis to determine future performance.
Running Backs’ Yards-Per-Carry
I recently visited New York City and passed a “psychic” in Times Square. She told me she could tell me anything about the future that I wanted to know (for $99, of course). I asked her if she could tell me how likely it is that Chris Johnson will repeat his stellar 2009 yards-per-carry (YPC). She walked away, and I never got my answer.
Nonetheless, I think statistical analysis and film study will give me a far more accurate prediction of Chris Johnson’s YPC than any psychic. Predicting the future isn’t about knowing conclusively what will happen, but rather deciphering the chances that a particular event will occur. Not to get too philosophical (hey, it’s what I do), but if the universe runs not through deterministic events, but rather random happenings, then it is impossible to “know” the future.
That doesn’t mean accurate predictions cannot be made, however. Weathermen often get a bad rap, but they are generally very good at what they do. Weather systems don’t function in a deterministic manner, such as balls on a pool table, but through random occurrences. Likewise, the 2010 YPC for each running back in the NFL is not somehow “determined” beforehand–but the probabilities of certain averages for particular players, I believe, are already written in stone.
So how are we to determine these probabilities? While they may “just come” to the New York psychic, I, unfortunately, have to do a lot more work. My methodology includes statistical analysis, so let’s take a look at some numbers.
First, we must note that the league-wide yards-per-carry average has skyrocketed in the past 13 years. After remaining relatively steady from 1974 to 1996, the yards-per-carry average has increased .2 yards since–a 5.11% increase. That number might not appear large, but it is rather staggering for a sample size of carries as large as the entirety of NFL running backs over an extended period of time.
Thus, there is a difference in YPC among eras, meaning if we are going to use the statistics from prior eras to broaden our sample size, we must account for this disparity. After correcting the YPC of “the old-timers” to more appropriately relate to the league-wide averages during their eras, we see that there is a rather significant correlation between a player’s YPC in year N and his YPC in year N+1 (the next season).
To see this formula and continue reading, please visit page 2 of 2.
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