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Correcting Auction Calculations in the VBD Application
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Posted 8/30 by Forrest Johnson, Freelance Submission to Footballguys.com
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The Current System
History
Back in 1996, the concept of Value Based Drafting (VBD) was born. The main
principle of this system is that "the value of a player is determined not
by the number of points he scores, but by how much he outscores his peers at
his particular position." Based on analysis of player values using this
system, the relative values of players across positions can be determined, and
an optimal draft priority can be created which enables comparisons of RB#13
to WR#3 and TE#1. Problem solved. Use VBD, dominate your draft, have a nice
day.
Note: If you are new to the VBD concept, please refer to the original VBD
article for additional
info.
The Current VBD Problem
Jump forward a decade to 2006. Today, more and more fantasy football leagues
have transitioned away from drafts and now select players via auctions. During
these past ten years, the VBD tool has been adjusted to calculate auction values
for players. So, you might ask, what's the problem? The problem is that the
VBD application doesn't calculate auction values correctly! Impossible? Well,
let's review actual VBD data and see if the math adds up.
Proof of the Current VBD Problem
The current VBD application allows two teams with the same numbers of starters
in each position scoring equal number of points, collectively, to cost very
different total auction amounts. If player value is measured based on projections,
and projections are used to calculate total points scored, this inequality means
the current VBD calculation of auction value isn't correct, since Team A's starters
scoring 400 points do not cost the same as Team B's starters scoring 400 points.
Here are two specific examples, but it is easy to find other examples.
Example #1
In a typical scoring system, and regardless of baseline comparisons, Tomlinson
scores 41 points more than Alexander (using 2005 projections). The auction
cost difference between these two players per the VBD app is $6 (out of $2000
total auction dollars: $200 * 10 teams). Tomlinson's cost theoretically should
equal Alexander's cost, plus the premium amount that 41 more points is worth.
We would therefore expect a 41 point premium above the baseline to be worth
$6 elsewhere in the valuations. But when we look at another RB that is scoring
41 points more than the baseline (Julius Jones is that RB for the baseline
I picked), the VBD auction value is $28. Even when we subtract the cost of
the baseline back we would have to get anyway (Thomas Jones for $10), We're
still at those 41 points costing $18!
These two examples cannot both be true. Looking at the fantasy points, we
should pay the extra $6 for Tomlinson, bank his extra 41 points, and then
take the baseline back (Thomas Jones for $10), resulting in a net savings
to me of $12 (Julius Jones $28 - Thomas Jones $10 - $6 extra paid for Tomlinson).
Tomlinson (+132 points over baseline) + Thomas Jones (0 points over baseline)
= +132 points over baseline (and we have $12 extra)
Alexander (+91 points over baseline) + Julius Jones (+41 points over baseline)
= +132 points over baseline (but we don't have $12 extra)
In this one example, $12 is 6% of the total salary for players and is a very
large error from an auction perspective.
Example #2
Let's look at this a different way to make sure we get inconsistent data from
two different methods. If we see inconsistency from two independent methods,
we can confirm a problem exists with the current model. Using the 2005 L1
VBD application with no changes, setting auction to "on", and generating
the cheatsheet (12 teams, 2 RB starters), let's look at a sample of 5 RBs
throughout the VBD range:
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Rk
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Player |
Auc$
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Points
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VBD
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1
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LaDainian Tomlinson |
73
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298
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157
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3
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Shaun Alexander |
66
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273
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132
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11
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Corey Dillon |
44
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231
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90
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17
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Brian Westbrook |
31
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208
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67
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28
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DeShaun Foster |
10
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142
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1
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So Tomlinson is projected to score 25 more points than Alexander. That performance
costs $7, or $0.28 per point. Alexander is projected to score 42 more points
than Dillon. That performance costs $22, or $0.52 per point. Dillon is projected
to score 23 more points than Westbrook. That performance costs $13, or $0.57
per point. Westbrook is projected to score 66 more points than Foster. That
costs $21, or $0.32 per point.
As you can see, the per-point costs are inconsistent, ranging from $0.28
per point up to $0.57 per point, or more than double the lower per-point cost.
This type of error naturally results in inconsistent auction costs. For a
two RB pair with identical projected performances, there is an $8 difference
in the auction costs.
Tomlinson + Foster = 440 points = $83
Dillon + Westbrook = 439 points = $75
On a per point basis, either Tomlinson is especially cheap or Alexander is
especially expensive. This inconsistency should not exist if the auction calculations
are working properly.
As can be seen from these two examples, the math doesn't add up. The VBD application
is telling me to stop bidding on the most valuable player, to overbid on lesser
players, and to spend more to build a team that gives less fantasy points than
a cheaper option. There is no rational explanation for this inequality, other
than an error exists in the calculation of auction values for the current VBD
application. Before we fix this problem, and it can be fixed, let's first document
what we want VBD to provide to us in an auction scenario.
The Auction Goal of VBD
The goal of VBD in an auction setting is to tell us the true theoretical auction
values for players. These values are derived from actual projections for players,
and are based on the specific scoring system in use, along with the roster requirements,
number of teams, and total team salary cap. All potential upside for players
is factored into the player projections. Teams with equal total points projected
from starting players should theoretically cost similar amounts. Auction values
should not be artificially adjusted to attempt to predict the behavior of other
owners.
Using VBD to establish auction prices for players is a very different story
than using VBD just to draft players. It's important to carefully differentiate
between drafts and auctions. Calculating auction value is a much more quantitative
exercise since it is necessary to be much more precise. In draft, the difference
between #1 and #5 player is 4 draft spots, which is half of a regular draft
round in a small 8 team league. In other words, this difference really won't
be seen since you take the best on the board for your team and precisely how
much better is less important. In auction, this early difference can be $30,
or 15% of the total dollars available to a team. Since every team has the opportunity
to bid on every player in an auction, every player has potential to be bought
cheaply. Therefore, calculating an accurate theoretical auction price is essential
to get the most for the money. This theoretical auction price tells an owner
when a player has value based on actual projections in relation to others' projections.
If a player is projected to be worth $30 and bidding stalls at $21, we know
exactly how much value we're getting from owning that player.
The New Concept
Two Types of Players
First, let's make sure we're clear on the meaning of some terms we are going
to be using. In the rest of this article, I have elected to call the top fantasy
players who historically command most all of the auction dollars spent in our
fantasy leagues (close to 85%), "premium players". The players we
purchase with the remaining 15%, which can include many every-week starters,
are termed "regular players". We will discuss this next, so it's important
we are clear on the language that we are using.
Setting the Baselines
Every year, there are discussions about where to set the baseline that is used
in the VBD calculations. Is it worst starter? Should we use last drafted? Is
it something else?
If the goal is to determine accurate auction values, the answer is that we
need to set TWO baselines within each position. It is obvious that we spend
money differently for premium players vs. regular players. Our baselines must
therefore account for these two different player populations. First, we must
identify the premium players so we can calculate their auction value in relation
to other premium players at different positions in standard VBD fashion. After
that's done, we then do the same for our regular players. It is essential that
the baselines be selected based on actual player scoring, and the actual break
points between premium and regular players within positions.
For example, in an 8 team, start 1 QB league with a scoring system where there
are 3 QBs scoring 50 points more than the rest of the QB pack, worst starter
will incorrectly set a baseline of the 8th QB, and last drafted might set a
baseline at the 13th QB (backups, etc). In actuality, nobody is paying a premium
after QB #3. As fantasy owners, we know we either want to step up and spend
to get one of these top QBs, or wait to get a regular QB cheaply while we spend
our money somewhere else. So, our premium auction value must use a baseline
of QB#4. Depending on the player spread, it's likely there is no reason to pay
any extra for QBs as soon as they level off, which means the regular player
baseline could be as shallow as QB#9. QB#10 and beyond are minimum bid players.
Allocating Auction Dollars
Once we have set the premium baseline for each position, we allocate ~85% of
all auction dollars to the total points scored by those players (after subtracting
the cost of minimum bids for all players). An owner can opt to allocate less
than 85% on premium players to build a deeper team. This is a customizable option
that each owner can set they way they want it. In setting this value, each owner
is effectively deciding how much to rely on premium players. Once the premium
baselines are set for each position, every point above the premium baseline
has a specific dollar worth. Let's look at a specific example of how this is
calculated in an 8 team league with a standard 1 QB, 2 RB, 3 WR, 1 TE, 1K, 1
DST roster, $200 auction per team, minimum $1 per player bid, with 120 total
players auctioned:
- ($200 * 8 teams) - (120 players * $1 min bid) = $1480 total auction dollars
available
- 85% * $1480 = $1258 for premium players
- 35 premium players identified using scoring drop-offs to set the premium
player baselines
- Total points scored by these 35 players above premium baselines = 1301
- 1301 premium points / $1258 for premium players = $0.967 per premium point
If a player is projected to score 30 points above the premium baseline, his
auction value is ($0.967 * $30 ) + $1. The extra $1 accounts for our removal
of the minimum bid dollars in the initial calculation.
After all the premium players are accounted for, this leaves $222 for all the
remaining regular players in the auction. The second baseline for regular players
is applied, and the remaining players total points above the regular player
baseline are calculated. In this example, these regular players score 1104 total
points above the regular player baseline, which equates to $0.20 per point.
All players below the regular player baseline are minimum bid players only.
Results
Using the 2005 data and this new system, here are the results of three randomly
selected teams. As one can see from the data, these randomly selected three
teams now cost the same amount and score the same amount. This is a significant
improvement from the current system, and means our auction values are now working
as intended.
- Team A
Manning, 384 points, $80
JuJones, 233, $24
Dillon, 231, $22
Marvin, 200, $53
Burleson, 158, $13
Moulds, 132, $2
Vinatieri, 142, $3
Pittsburgh, 190, $5
$203 spent, 1670 total team points.
- Team B
Collins, 304 points, $6
Alexander, 273, $61
JLewis, 216, $20
ChadJo, 203, $57
AndreJo, 180, $35
MClayton, 154, $10
Janikowski, 128, $1
Baltimore, 214, $14
$204 spent, 1670 total team points.
- Team C
Favre, 287, $3
Tomlinson, 298, $85
Portis, 230, $22
Harrison, 200, $53
D. Bennett, 171, $26
Bruce, 146, $6
Wilkins, 125, $1
Patriots, 200, $8
$205 spent, 1659 total team points.
The fact we're that we're dead on for two typical teams, and within 10 points
for a third team is very encouraging. All three of these example teams incorporate
a mix of premium and regular players. With this new system, all of the large
inconsistencies we observed in the current auction value calculations have been
resolved.
Accomplishing the Two Line Fit
Since we are effectively using a two-line fit to calculate our theoretical
auction values, there is an additional interim step required to ensure the intersection
of these two lines is a smooth transition. The theoretical premium player baseline
must be reviewed to ensure a smooth transition from premium to regular players.
It is sometimes necessary to add one or two premium players to the regular player
pool, or add one or two regular players to the premium player pool. The premium
player baseline is established by the owner for each player position, however
an adjustment of one to two players is sometimes necessary to prevent an artificial
drop between two players due to mathematical artifact. This is the largest mathematical
hurdle to automating this process, and is basically a smoothing of the transition
from premium to regular players. Once the initial data are calculated using
the owner input data, it only takes one iteration to smooth the two line fit
into a model that doesn't artificially skew the results based on the intersection
of the two projection lines.
Applying the New Concept
The changes to VBD to apply this new concept are as follows
- Based on the actual scoring data generated from initial calculations using
the league specific information, the owner sets the theoretical premium player
baselines for each position, and the regular player baselines for each position.
(Note that less precise default selections would be included in the standard
VBD application to help those who aren't able to do this on their own.)
- Owner has option to use default 85% of auction dollars for premium players,
or change to higher or lower number (e.g., higher amount would result in more
dependence on premium players).
- Spreadsheet then uses the owner baseline inputs to calculate initial auction
values, and then mathematically smoothes the two-line intersection to provide
the final auction values.
Summary and Conclusions
The current VBD application allows two teams with the same numbers of starters
in each position scoring equal number of points, collectively, to cost very
different total auction amounts. There is no rational explanation for this inequality,
other than an error exists in the calculation of auction values for the current
VBD application. This error has been proved to exist via two separate methods.
The goal of VBD in an auction setting is to tell us the true theoretical auction
values for players. Teams with equal total points projected from starting players
should theoretically cost similar amounts. The proposed system accomplishes
this goal.
In closing, I have created a spreadsheet that uses the scoring projections
from the current VBD application and then implements the proposed system. This
spreadsheet is available by request (email me at inca911@hotmail.com) or by clicking on the link below.
Updated Spreadsheet for 2007
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