I wrote this article for Rotoworld and it was published 7/15 – you can find the original version here.

Outliers as the norm

In fantasy football, especially when it comes to injury, we tend to look at outliers as the norm. It is the human condition to think that a single event we observe in the recent past will apply to most in the future.

An example could be thinking that Adrian Petersons recovery in 2012 from a torn ACL was normal for all players coming off an ACL injury. Another example could be to think that a first year wide receiver who gets injured this year during training camp and misses the first 4 games is primed to light up the scoreboard because that’s what happened with Odell Beckham Jr in 2014.

This bias is dangerous in fantasy football because it sets up the expectation of the extraordinary being ordinary which is not a great way to make decisions.

The reality is that training camp injuries have a big effect on the injury probability of a player during the regular season. We want to show you how to leverage preseason injury information in a way that helps you accurately draft players based on what their expected outcome is at the end of training camp versus what it was before.

Injury data

We dug into the last two year’s preseason injury data and compiled a list of players that were injured in the preseason. What was great about the dataset we looked at is that the number of players injured in the 2013 and 2014 preseasons is very similar (39 in 2013 and 41 in 2014). So while the sample set is small (only 80 injuries) and does not exactly constitute a trend, it’s interesting to see the similarities between the two years.

This is outlined in the table below and quick definitions of the columns are:

Reinjured: A player was injured in the preseason and then suffered another injury during the regular season.

Not reinjured: Players who they suffered a preseason injury but were able to play a full season of 16 games.

IR/Severe: These are players who suffered an injury in the preseason so severe it caused them to be placed on IR or miss 4 games or more. Examples here would be Jeremy Maclin tearing his ACL in 2013 and Charles Sims missing 10 games in 2014 due to an ankle injury suffered in the preseason.

Team Depth Chart: This is to identify the roll the player has on the team and is not to be confused with fantasy production. An RB1 on a team has in theory a bigger workload than an RB2 or RB3 and is therefore more exposed to risk of injury regardless of fantasy production.

A preseason injury is measured as any injury that causes the player to more than a week of practice. An in-season injury is defined as any injury that cause the player to miss a game.

2013

Re-injured Team Depth Chart Not re-injured Team Depth Chart IR/Severe Andre Brown RB1 Andrew Hawkins WR3 Jeremy Maclin Arian Foster RB1 A.J. Green WR1 Joe Morgan Cecil Shorts WR1 E.J. Manuel QB1 Danario Alexander Chris Ivory RB1 Earl Bennett WR4 Dennis Pitta Dwayne Allen TE1 Jamaal Charles RB1 DuJuan Harris Hakeem Nicks WR2 Montario Hardesty RB3 Dustin Keller Josh Boyce WR4 Pierre Garcon WR1 Kevin Kolb Julio Jones WR1 Robert Turbin RB3 LaMichael James Justin Forsett RB2 Terrance Williams WR2 Latavius Murray Lance Dunbar RB3 Joel Dreessen TE2 Marcedes Lewis Le’Veon Bell RB1 Mikel Leshoure Marques Colston WR1 Percy Harvin Randall Cobb WR2 Ryan Williams Stevie Johnson WR1 C.J. Anderson Victor Cruz WR1

2014

Re-injured Team Depth Chart Not re-injured Team Depth Chart IR/Severe Allen Robinson WR1 C.J Anderson RB1 David Wilson Andre Ellington RB1 Chris Ivory RB1 Domenik Hixon Andre Johnson WR2 Isaiah Crowell RB2 Isaiah Pead Arian Foster RB1 Kenny Stills WR3 Jared Abbrederis Bernard Pierce RB2 Mike Wallace WR1 Kendall Hunter Cam Newton QB1 Nate Burleson WR4 Kevin Norwood Cecil Shorts WR2 Odell Beckham WR1 Marcus Lattimore Charles Clay TE1 Pierre Garcon WR2 Marvin Jones Chris Polk RB2 Riley Cooper WR3 Sam Bradford DeSean Jackson WR1 Scott Chandler TE1 Charles Sims Jonathan Stewart RB1 Troy Niklas TE2 Vick Ballard Knowshon Moreno RB1 Wes Welker WR3 Marqise Lee WR2 Peyton Hillis RB2 Steven Jackson RB1 Tyler Eifert TE1 Austin Seferian-Jenkins TE1 Toby Gerhart RB1

2013 2014 Total Total injured in preseason 39 41 80 IR/Severe 14 12 26 Re-injured 15 18 33 Not Re-injured 10 11 21 Percentage of players reinjured 60% 62% 61%

From this dataset it appears that if a player gets injured in the preseason with an injury that is not severe, they will get reinjured on average 61% of the time.

However, if we dig a little deeper it gets even more interesting.

One of the things that jumps out here is the role of the player on their team and how that relates to the “re-injured” and “not re-injured” list. For the most part the “re-injured” players are first string players whereas most of the players who are “not reinjured” are second string players. Which makes sense as those first string players are those on the team who get the ball more often and are more exposed to risk of injury.

If we filter out the second string players (WR3, RB3 and TE2) from the list here is what it looks like this:

2013 2014 Total Total injured in preseason 39 41 80 IR/Severe 14 12 26 Re-injured 15 18 33 Not Re-injured (featured players only) 5 6 11 Players re-injured 75% 78% 77%

As you can see the percentage chance of re-injury jumps significantly to a whopping 77%!

Obviously this is partly a function of the fact that the sample size is small, but this finding lines up so snugly with our principles on how we approach injury probability that it cannot be discounted:

Players who have suffered a previous injury are more likely to suffer another injury than players who have not suffered any injuries

The bigger the role a player has on the team the higher the risk of injury due to more exposure to the ball

So if player who is in a featured role on his team gets injured during the preseason severely enough to miss a big chunk of preseason training there is a very good chance that they will miss time of the regular season due to injury.

Action to take

The approach to players who get injured in the preseason should be the exact same way a car insurance company hikes up your premium if you have an accident. Insurance companies don’t care who was at fault when you have an accident. They care when the last time you claimed for an accident in order to figure out how much to charge you so that their costs are covered and that they make money (your value to them).

It’s the same when looking at players who get injured in the offseason…

Featured players who get injured in the preseason are very likely to get injured in the regular season. As such the valuation you have placed of where to draft that featured player should change if he gets injured during the preseason.

In the book “The Lean Startup” – Eric Ries speaks about the concept of a pivot. Most startup companies who develop a successful product reach a point at which they need to decide whether to pivot or persevere. A pivot is defined as change in direction based on new information about the product, strategy and engine of growth. It’s the same for fantasy football. As new information arrives we invariably need to make decisions whether to pivot or persevere as to where we value certain players at. This process starts in the preseason. Player rankings are now established based on the information everyone has had at hand so far. As news of injuries comes in be prepared to pivot and adjust accordingly so that you are not left behind.