Sports Injury Predictor has partnered with Rotoworld in 2015 to give you an even greater chance winning your league this coming season. As a quick introduction we have an algorithm that figures out which players are more likely to get injured in the coming season. We’re going to isolate some of the more risky high value players as well as point out who the safer players are as we help you ramp up your research for your upcoming drafts. Follow us on Twitter @injurypredictor and check out our site www.sportsinjurypredictor.com for more information.
As we get into training camp and the preseason and your draft research begins to dial up you’re going to hear a lot of information about injuries. For the most part it’s an exercise in finding signals and ignoring noise. Signals are aspects we should pay attention to as predictors of things to come and noise represents inputs that are misleading and have no predictive value.
When we were building our algorithm we tested several factors to see how much of a weight they should be given to predict the likelihood of injury. Here are some the factors we found to be signals that we included in the weighting of our algorithm as well as some that we discovered were noise and safe to ignore.
Age: The older a player gets the more “injury prone” they are
Noise
You will read or hear that certain players reach a certain age at which they begin to “break down”. For running backs the age is usually around 27 and for wide receivers it’s usually given at around 29.
We tested age extensively to see if it could be used as a signal and we found no correlation between age and injury. Yes there are fewer 30 year old running backs in the league than 25 year old ones, but this is more of a result of survivor bias than players reaching a certain age that makes them more likely to get hurt. Survivor bias means that those players who are not durable enough will actually get injured younger and leave the league earlier. The players who are older are therefore the more durable ones (as they have survived) and LESS likely to get injured.
You do see far fewer older running backs than younger ones – but so long as they don’t have a significant injury history that would have put them at risk anyways (Willis McGahee/Ahmad Bradshaw) they’re more likely just to fade away due to a deterioration in production (Michael Turner/Chris Johnson).
If we take a snapshot of 2014 injuries and the length of time players had been in the NFL for we see the following:
The graph above demonstrates that last year 42% of all players that had been in the NFL for 3 years or less suffered an injury that held them out of at least one game. In contrast, only 25% of players going into their 10th season suffered an injury that kept them out of more than one game.
What the graph does not show is that 48% of all rookies were injured or missed at least one game.
Why this is important
With all the noise around injury and older players there are some great value plays available. Marshawn Lynch and Justin Forsett are two players who are available at great ADPs because of injury fear due to age (they both have very light injury histories). If Lynch was 25 coming off three seasons as he has just had he would be the uncontested number 1 pick however people are afraid of the age. Capitalize on this and grab him and other older players knowing that the injury risk is actually less than what it is for similar volume players who are younger in the NFL.
Size: Smaller Running Backs are more likely to get injured
Signal
Size is a good signal for running backs in terms of durability and the ability to stay on the field. We could not find an optimal weight or height but we did find a correlation between body mass index (BMI) and injury. We worked out body mass as BMI = weight/(Height X Height).
The graph below shows 70 running backs that were active in 2014. The bar on the graph indicates whether they had missed 3 games or more within the last 3 seasons. The lighter built players to the left of the graph are clearly injured more frequently than their heavier counterparts to the right of the graph.
Why this is important
RBs who are on the lighter side such as Jamal Charles and Chris Johnson are outliers. Most players with that lighter body type do not have longevity in the NFL. When you hear buzz starting to build around a smaller player as having physical comparables to Jamal Charles it should be seen as a red flag and expectations should be adjusted knowing that he is an anomaly at a position that emphasizes size.
Position: Running Backs get injured more than any other position
Signal
Running backs do get injured more frequently than any other position. The pie chart below is percentage of total injuries we have tracked for the seasons 2012 – 2014. We divided the injuries at each position by the total number to get the share of injury that each position takes. While it may look close (only 3 percentage points difference between wide receivers and running backs) the gap is actually a lot wider than it seems because there are far fewer RBs than there are WRs.
Why this is important
This adds strength to the zero running back strategy of fading running backs in early rounds of fantasy football drafts. Without knowing which running backs are more likely to get injured one just has to know that running backs are on average more likely to get to injured as a group. It’s preferable to invest high draft picks in wide receivers, as it’s a less volatile position that sees similar levels of production.
Length of the season: As the season progresses players are more likely to wear down and get injured
Noise
Preseason and the first 8 weeks are the most likely time for a player to get injured. This is yet another example of survivor bias at work. Those players who are going to get injured do so early on in the season. The players who make it to the final games of the season are actually less likely to get injured.
Last year there were twice as many injuries in September as there were in November and more in the preseason and September than November and December combined.
Why this is important
This is something to keep in mind as your bench evolves over the course of the season as well as certain trades come into the picture. Players who have a high injury risk but who don’t get injured early on in the season may be worth making a move for in a trade proposal knowing that they have made it through the dangerous period.
Previous Workload: Running backs who have touched the ball more than (insert-arbitrary-number-here) times the previous season are more injury-prone the following season
Noise
The players who step on to the field on a Sunday are the elite of the elite. They are some of the most athletic specimens to walk the planet. Not only are they in a physical state that 99.99% of the world’s population will never experience but their every waking moment is governed by teams of doctors, nutritionists, physiotherapists and conditioning coaches that ensure they are in a constant state of peak condition. And they have been doing this all their life.
To assume that there are a finite number of hits, yards, carries, receptions or whatever you want to place a number on as an indicator of injury ignores the fact that the people we are discussing are elite athletes who are paid huge sums of money to show up every Sunday. It also ignores that every player is different. 250 Lynch carries are way different to 250 CJ?K carries.
There is no statistical evidence that we have encountered that can show how previous touches or yards rushed for in prior seasons will determine the likelihood of a player getting injured the following season.
We look at injury as a linear event. You start at 0 (not injured) and the more you play you will move towards a 1 (injured). What exposes you to injury is how many times you WILL touch the ball in season and not how many times you HAVE touched the ball. When you start to think of it this way you will see a flow develop between the projections for each player and the associated injury risk. The more exposure to the ball the more exposure there is to risk.
Rookies by far have the largest injury risk heading into the NFL. They have not had any NFL carries.
Why this is important
Never ever fade a player because of his previous workload. In fact – look for players coming off a heavy workload but with little injury history or a clean preseason in which they were able to stay healthy, as there is a great chance they will be undervalued due to fears of injury.
For more information check out our site www.sportsinjurypredictor.com, follow us on Twitter @injurypredictor or get in touch with jake@sportsinjurypredictor.com.
