Several months ago I laid out a simple model for forecasting fantasy football performance. My post included a table ranking players by value for draft purposes. Appropriately, in our league at Nielsen I used my own model to draft (selecting Ray Rice in the first round, followed by Victor Cruz and Wes Welker). I screwed up in a later round and accidentally selected Jason Whiten instead of Matt Ryan – but other than that I strictly followed the advice of my blog: always choose the highest ranked player from positions that needed to be filled.
So how did I do? Well, I finished third out of twelve – not bad. Let’s take a retrospective look at my model to see how accurately I predicted the 2012 fantasy football season.
My previous post provides actual 2012 statistics for all positions. I scored each player and compared to my projections. Note that my projections did not include players who did not participate in the 2011 season (e.g. Jamaal Charles) or rookies (e.g. RG III), so they are not included in the analysis. If I regard the difference between actual and projected fantasy points as “error”, then I can compute R^2 to summarize fit. I computed R^2 for two projections:
- Project 2012 points as equal to 2011 points (“2011” in the table below)
- Project 2012 points by adjusting 2011 points as described in my post (“Model”)
The results are as follows:
| Pos | N | 2011 | Model |
| DEF | 29 | 0.899414 | 0.899414 |
| K | 26 | 0.961511 | 0.961511 |
| QB | 31 | 0.909683 | 0.887465 |
| RB | 101 | 0.774406 | 0.797133 |
| TE | 78 | 0.81725 | 0.824893 |
| WR | 124 | 0.806109 | 0.810808 |
The overall R^2 for the model is around 0.852. I didn’t really dig into the details too much, but I think we can reasonably conclude that:
- Kickers and Defense are pretty darn stable (probably because they largely depend on the strength of the team and opposition, which does not generally massively change between seasons).
- RB performance was the hardest to predict.
- The model worked in the sense that most positions ended up with better R^2 than if I had simply used 2011 numbers.
- The exception is for the QB position, which perhaps implies that my assumptions about touchdown production do not apply to the QB position.
In the table below I compare the points per game projected by the model (Projected) with the actual number of fantasy points in 2012 (Actual) and the relative error. I highlight a row green when the relative error is less than 10%. If it is less than 25% it is yellow, and red otherwise.
|
Name |
Pos |
Projected |
Actual |
Rel. Err. |
|
Drew Brees |
QB |
20.65682 |
21.59875 |
0.043611 |
|
Aaron Rodgers |
QB |
22.32247 |
21.35625 |
0.045243 |
|
Tom Brady |
QB |
20.06681 |
21.2675 |
0.056456 |
|
Cam Newton |
QB |
19.92028 |
20.17875 |
0.012809 |
|
Adrian Peterson |
RB |
13.7407 |
19.0875 |
0.280121 |
|
Matt Ryan |
QB |
15.70105 |
19.05375 |
0.17596 |
|
Tony Romo |
QB |
15.42652 |
17.18875 |
0.102522 |
|
Matthew Stafford |
QB |
18.70318 |
17.08 |
0.095034 |
|
Ben Roethlisberger |
QB |
14.58558 |
17.06154 |
0.145119 |
|
Arian Foster |
RB |
18.69446 |
16.38125 |
0.141211 |
|
Andy Dalton |
QB |
12.47327 |
15.6725 |
0.20413 |
|
Marshawn Lynch |
RB |
13.48645 |
15.4125 |
0.124967 |
|
Josh Freeman |
QB |
14.20246 |
15.40625 |
0.078137 |
|
Michael Vick |
QB |
21.37533 |
15.168 |
0.409239 |
|
Carson Palmer |
QB |
20.68852 |
14.688 |
0.408532 |
|
Eli Manning |
QB |
16.32711 |
14.5575 |
0.12156 |
|
Joe Flacco |
QB |
12.35432 |
14.555 |
0.151198 |
|
Kevin Kolb |
QB |
11.33343 |
14.12667 |
0.197728 |
|
Matt Schaub |
QB |
22.60787 |
13.96375 |
0.61904 |
|
Sam Bradford |
QB |
16.83711 |
13.92375 |
0.209236 |
|
Ray Rice |
RB |
17.53886 |
13.88125 |
0.263493 |
|
Calvin Johnson |
WR |
15.14139 |
13.775 |
0.099193 |
|
Brandon Marshall |
WR |
9.919735 |
13.55 |
0.267916 |
|
Ryan Fitzpatrick |
QB |
13.05769 |
13.35625 |
0.022354 |
|
C.J. Spiller |
RB |
7.19662 |
13.26875 |
0.457626 |
|
Philip Rivers |
QB |
14.7622 |
13.015 |
0.134245 |
|
Dez Bryant |
WR |
9.147546 |
13.0125 |
0.297019 |
|
Rob Gronkowski |
TE |
13.32919 |
13 |
0.025322 |
|
Stevan Ridley |
RB |
3.349849 |
12.4625 |
0.731206 |
|
A.J. Green |
WR |
9.735794 |
12.4375 |
0.217223 |
|
Demaryius Thomas |
WR |
6.994023 |
12.3375 |
0.433109 |
|
Jay Cutler |
QB |
20.61836 |
12.308 |
0.6752 |
|
Frank Gore |
RB |
10.8703 |
12.3 |
0.116236 |
|
Alex Smith |
QB |
12.57711 |
12.268 |
0.025197 |
|
LeSean McCoy |
RB |
16.10583 |
12.10833 |
0.330144 |
|
Christian Ponder |
QB |
14.64461 |
12.04375 |
0.215951 |
|
Jake Locker |
QB |
9.065129 |
12.01273 |
0.245373 |
|
Chicago Bears |
DE |
8.4375 |
11.875 |
0.289474 |
|
Matt Forte |
RB |
14.61648 |
11.82667 |
0.235892 |
Nathan Brixius 