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29 Jun 2009
Running Backs' "Football Age"
Reader Mike sends in this link to research he's done regarding the true "age" of running backs.
22 comments, Last at 05 Jul 2009, 3:59pm by b-rick
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Re: Running Backs' "Football Age"
Interesting, if a little confusing; I noticed Edge had 10 attempts left, worth 140 yards, and over a year and a half left. Am I missing something, or are these variables not connected at all?
Say, he has 10 attempts left OR 140 yards OR 1.5 seasons, whichever occurs first?
Re: Running Backs' "Football Age"
It's really hard to take his method seriously when he's got Mendenhall set for 3 yards per carry for the rest of his career and Felix Jones set to pull down about 9. I guess Mendenhall could possibly bust, but to predict that is a bit of a reach. I'll bet whatever you want that Felix Jones doesn't have 9 yards per carry for the rest of his career.
Re: Running Backs' "Football Age"
He noted at the end that this was not a projection tool, per se. It is a tool to figure out about how long each player will last under their past workload and the past performance of retired running backs.
Re: Running Backs' "Football Age"
I think with the younger backs it's hard to predict because they have very little data to go on, as he states in the article.
Re: Running Backs' "Football Age"
I can't tell what he did or whether this research is any good.
Re: Running Backs' "Football Age"
Glen Coffee: All-Pro in 2033.
Methodology please!
Let me second all the comments above. Otherwise it's pointless to discuss.
Re: Running Backs' "Football Age"
Take Chris Johnson, Matt Forte, and Jon stewart. Johnson last year had the highest yards per carry and the prediction gives him the nod in that category. Forte had a shit yards per carry and predicts he will pull an eddie george... a long career with good career numbers off of bad production per play. Jon Stewart scored a lot of touchdowns on limited carries... giving him the best likelihood out of the three for getting the most touchdowns because A) hes the biggest and most likely to get goalline carries B) he so far has used the least amount of gas to get those touchdowns based on career carries and age C) put up very good production when his number was called.
This isnt a prediction. Its a numbers bending grid helping us make the call on how well players will perform.
Re: Running Backs' "Football Age"
Is this validated against anything? Like if you take a retired RB and look at his numbers through X years, and how much is left in his "tank," does it match up to his actual retirement? Does the production trail off in any predictable way?
I just don't get how this was compiled, or why we should care. All I see is a table of confusing spreadsheets and predictions that don't make sense.
Re: Running Backs' "Football Age"
This explains partially what he did:
"...you have to use a combination of numbers to say how much a running back has left," and "... used data from the top 200 retired running backs based on attempts taken from the great http://www.pro-football-reference.com/ , and fit a polynomial line to it." He appears to have derived a set of equations based on retired RBs who had a lot of carries in their career. He then plugged in data for current RBs to estimate their expected longevity.
He could validate it as you suggest, if he had another pool of retired running back data to dip into; however, had he provided additional information, such as the the goodness of fit or the R square of his equations, that would not be necessary, as we would know the robustness of his model.
What is unclear, is:
Why he chose 65 as a retirement age? This is a transformation, that adds to the confusion, as noted below.
Are "football years" linear, that is, is the difference between 25 and 26 the same as 29 and 30? Given that a polynomial line was (presumably) fit to the data, my guess is no.
Why limit the sample to 200? On the PFR list, there are over 200 retired RBs.
Is "amount left in the tank" (or ALtT) and or Football Age (or FbA)the best measure, and what do they mean? Are ALtT and FbA combinations of variables like AGE, Att Lft, Yrds Lft, TD Lft, Rec Lft, Rec Yds Lt, Rec TD Lt, Sea Lft, and Gft and therefore more robust predictors than any of the individual variables or are Att Lft, Yrds Lft, TD Lft, Rec Lft, Rec Yds Lt, Rec TD Lt, Sea Lft, and Gft somehow derived (predicted ) by ALtT and/or FbA?
A lot of the confusion in this article is due to a lack of clarity in the writing. Some of this appears to be an attempt to be brief and concise. Nonetheless, this is a shame, because, if the models are accurate, there is some interesting information in the article.
Re: Running Backs' "Football Age"
I assume he picked 65 because that is the "normal" retirement age for an American, and he just normalized his numbers to fit that. He could have picked any age really.
Re: Running Backs' "Football Age"
You've really got to think about what statistical methods are going to fit the kind of data he's trying to model here. I almost think it should be modeled as a survival curve, with an arbitrary endpoint of 'negligible production,' or perhaps retirement.
Re: Running Backs' "Football Age"
I don't care what any of you guys say, I love this... According to his numbers, Jonathan Stewart is going to be the best running back by the time all these guys are retired.
Re: Running Backs' "Football Age"
I kind of like this, and as an AFC fan not rooting for the Steelers, I was glad to see that Willie Parker, whom I regard as a "kid," is 28 already!
One of the shortcomings is that this necessarily uses, not only past performance, but past usage as a predictor. What would this methodology have said about Randy Moss after his two years in Oakland? It would probably have given him a year or two of moderate production and then a lifetime of shooting hoops in his backyard. But that wouldn't have been accurate. Changing usages--like Addai going from a true 2-back system in 2006 to a solo career in 2007, to an injury-plagued hybrid last year, and now what we expect to be a shared load in 2009--are very hard on an approach like this. How can is predict if the future usage is so different from the past?
My guess is that injuries, which in my mind are generally a cumulative thing (except for Fred Taylor) are not factored in either.
Interesting how many of the Red and Gold guys are F/A's... I assume the league shares some of the snetiment that these guys are oon balding tires.
Oh, and NO WAY does Shaun Alexander have more gas in the tank than Edge. 3 more years and 1,000 more yards? To quote Elastigirl... I don't think so. I don't think so.
As pointed out above by Keith (#1), 9 attempts in 19 games for Edge? I guess it also does not take into account the fact that guys would go postal, demand a trade, quit, or take up competitive crocheting rather than average half a carry per game over more than one season. One of the great things about FO is the guys don't just accept whatever resuts the computer spits out--it has to pass a test of reasonableness and gets vetted with great brutality by a pitiless mob of starved cannibals (us). There are times the formulas are tweaked because "something just wasn't working right." And other times ("Dear Aaron, please fix this because it constantly under-projects the Colts annual wins by about 3....") that the system works fine for 30 out of 32 teams, so it's left as-is.
Re: Running Backs' "Football Age"
I was glad to see that Willie Parker, whom I regard as a "kid," is 28 already!
Does Parker's barely having played in college work to his advantage here?
Re: Running Backs' "Football Age"
So there's no consideration for injury history? Seems to me like that would be more of a factor than age and almost as much of a factor as carries. Also, is there a way to calculate tackles? A lot of HOF'ers I'd imagine are a lot like LT, where they have an absurd number of carries, but comparatively large proportions of TDs and runs out-of-bounds.
Re: Running Backs' "Football Age"
It most certainly wouldn't have been included in this analysis, but I've always wanted to see a "shot's taken head on" versus longevity study. It's similar to the one you propose, where TDs and OOBs aren't that detrimental to a RB, but also takes into account glancing blows.
Great boxers still get hit, but know how to get out of the way enough so that the bulk of the force is thrust past a just stung cheek.
Players like Earl Campbell, Brandon Jacobs, Jamal Lewis take so many hits straight on that it has to be brutal to career longevity even though they're large. Whereas guys like Warrick Dunn, and I'd say maybe the best of these, Marcus Allen, seem to be able to get just out of the way of a massive hit.
I know it would be a very hard (and semi-subjective) study, but I'd like to see just how important it is to go down when you know you're going down.
Re: Running Backs' "Football Age"
Any touch where the clock didn't stop at end of play, plus some fraction of any touch where the clock did stop. You could probably use guesswork to assign some fractional value for the wear-and-tear of a non-carrying play vs. a carry with a tackle vs. a carry ending OOB or in a TD. But you could probably just determine the difference between carries and plays-at-large to approximate it (maybe undervaluing the difference, actually).
Re: Running Backs' "Football Age"
That won't work any more the clock keeps running when you go out of bounds outside of the last 2 minutes of the first half or the last 5 minutes of the 2nd half.
Re: Running Backs' "Football Age"
Hmm... then you could easily compile old data for statistical purposes, but going forward you'd need to track it by tracking credit for tackles.
Re: Running Backs' "Football Age"
according to this article, Glen Coffee is 2 years old...
Re: Running Backs' "Football Age"
This is a overly-complicated and uselss way to analyze and predict the production of a RB.
Aside from injuries and the loss of critical team-mates (espcially OL) in free agency, the only accurate statistical predictor is 370.
It seems that many teams have begun to adopt the principal of platooning RBs, or at least limiting the touches by their featured guy. Perhaps the analysis from FO has something to do with that.
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