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Saturday, 25 August 2012

GUEST ARTICLE: Snakes and Pains, by Nick Wadlow

It started when Chandler Harnish became the latest Mr Irrelevant at the end of April - my mind started to turn away from reality and towards the abstract. As July faded into August more and more time was spent cruising the internet looking for snippets of information. Beat writers in Chicago, San Francisco and Baltimore, NFL players on twitter, podcasts from some guy named Nate and his narcissistic friend from just outside Hartford Connecticut – I consumed them all hungry for the information that might give me the edge come season’s end. MJD’s holdout, Jamaal’s knee, Chad’s new name, Peyton’s neck, Dez’s mother and DUI charges to numerous to mention gained an unhealthy relevance for me. It’s nearly fantasy football time. I have hinted, bribed and cajoled my way into some new leagues, and even taken the commissioner’s job in one I played in last year.

I guess you could say I’m keen for the season to start, and I guess you’d be very right.

Before the points can start to be tallied however, the teams need to be decided, before the game can begin – the draft must happen. This is where the fun begins.

Like I say I have spent too much time thinking about fantasy football in the last few months. I’ve mainly been thinking about how I going to try and win, and it strikes me that the draft is crucial. This however, is not a new insight, everyone knows that the draft is crucial – and everyone also knows that where you pick in the draft can be pivotal. What I got to wondering though is how important is draft position, what’s the best place to pick and can you quantify the value of each different spot?

Relative value of a draft spot

Most people who draft (rather than have an auction) do so using the snake system, you define an order, pick from first to last and then reverse the order for the next round, picking from last to first so to speak – then repeat until your rosters are full. This system is trying to address the fact that the value of the players available will decrease as the best players will get taken early – unless your drafting with fools....insert your own jokes about the Jacksonville front office here, I suggest you work the line “punters are people too!” into it if at all possible.

The trouble is that this is a fairly simple solution, and it’s widely recognised as unfair. Everyone who has ever celebrated a 1st or 2nd spot in the draft or bemoaned their ill fortune at having to pick last has implicitly acknowledged that they don’t believe ‘the snake’ evens out the odds. I wanted to understand if this impression we all have if accurate and if at all possible to measure the relative advantage each draft position gives you.

What I wanted to do was place a value on each player, then look at which players were available at each pick in the draft – and then sum up the value for the players chosen for each picker. By then comparing the total value available to each picker we can make a comparison between them and see how big of a disparity exists – if any.

There are two main wrinkles to iron out in this approach however.

Firstly, how do you accurately quantify the value of players in such a way that you can make meaningful comparisons across different positions? A QB averaging 15 points per game is worth a lot less than a TE averaging the same amount.

Second, how do you adjust for roster composition? If every time your pick come up the ‘best’ player to pick is a QB you are going to be forced to pick less valuable players.

The first wrinkle is actually not a new problem, fantasy players and analysts have been thinking about this for a long time and there are many different established techniques for comparing players across positions.
The one I decided to use is called VBD, this stands for Value Based Drafting, which is a bit of a misleading name, but it’s a pretty useful concept. A player’s VBD is their expected number of points minus a baseline point total specific to their position. The baseline is normally either an average for players of that type, or the expected value of a waiver-wire pick-up. What we are trying to get to with VBD is how much of an advantage does a specific player give me over a likely replacement.

The second issue is slightly tougher. The way I adjusted for this was to look at the value available in the vicinity of the draft pick being made, albeit weighted heavily towards the actual number of the pick. This means that if when I am considering the value of pick number 15 for example I’ll account for the possibility that the 13th or 14th most valuable player might still be available, or that the picker might have to reach down a spot or two to avoid, for instance, getting two QBs in the first two rounds.

So now we can rank the players according to their VBD score, and unsurprisingly this looks pretty similar to a list of players ordered by VBD – it turns out that on average fantasy football players make decent decisions. Then we sum up the value available to each spot in the draft and we get a total value and an average. We can then also turn this average into an expected number of points per week to get a feel for how significant the effect is.

The table below shows how each position is valued using this technique in a 10 team league with standard ESPN scoring. The difference isn’t huge, but the 4 point weekly swing between first and last is equivalent to a quarterback touchdown and is certainly large enough to have turned losses into defeats in a good few matchups in most leagues I’ve seen.

The other thing that jumps out at me here is that there are several groups. There is not much to pick between 1,2 and 3 and then there is a big drop off to 4,5 and 6 which are also in a group, below that it just tails off and I definitely don’t want to be picking last.
Draft spot
Relative Value
Weekly pts Difference
1st
111%
2.0
2nd
110%
1.8
3rd
109%
1.6
4th
101%
0.1
5th
98%
-0.4
6th
99%
-0.3
7th
95%
-0.9
8th
94%
-1.2
9th
93%
-1.3
10th
91%
-1.6

So if you don’t have one of the top three draft places is it even worth showing up, or are you doomed from the start? Absolutely not, this is a small effect and it’s going to be swamped by any number of things happening in your league – injuries, rookie sensations, player slumps and great waiver wire pick-ups all have the potential to be worth far more than a couple of points a week. That said the effect of small advantages like this should show up in a big enough sample size and come the end of the year I’d love to get my hands data that showed league results by draft order and I’d be willing to bet players in the first three positions win more than their 30% of ten team leagues.
The annual White House fantasy football draft is often
a solemn event


- Nick Wadlow (@nickwadlow)
- Guest Writer

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