Tuesday, April 29, 2014

Do NFL teams draft proactively or reactively?


The NFL does not have a reputation as a forward-thinking league. It tends to get caught up in trends with a couple teams pioneering something (the wildcat formation, big CBs) and others following the next season.

Given that players are locked into rookie contracts and tend to improve in their first few seasons, the draft could be an opportunity for teams to bet on what positions will be in demand – and higher priced – a couple years in the future while their players are still locked up on rookie contracts.

By looking at whether the allocation of value in the draft more closely matches the allocation of salaries in the prior year, current year or next year, we may be able to tell whether teams are being proactive or reactive in how they draft relative to where the league spends money.


The amount of draft value allocated to each position (as calculated by the Sports + Numbers draft value chart) will be compared to the % of spending on top players at each position, with the number of players included determined by the number of starters for that position. QBs, for example, will have the top 32 considered while Tackles will have the top 64. This may get me into some trouble with RBs (top 48, with FBs included), WRs (top 80) and DBs (top 128), but helps slim down the number of players who have to matched between the two data sets.

As a quick check to make sure we avoid double-counting allocation on rookies, we need to see how big their impact is on the salary data set. Since the first round contains more than 40% of the draft value and the highest salaries the results might show correlation with the current season when really the data just correlates with itself.

Once we select down to starters in the data set[1] the players in their first season represent only 5% of the group. The salary cap percentage-weighted distribution looks like this:


Since rookies only make up 3.6% of the salary we can be reasonably confident – a phrase I use way too much – that they will not screw up the analysis. 

Even more than the draft value, the salaries that make it into the top 32/48/64 at each position are concentrated at the top. In the first several seasons in the league first rounders make up almost all of those included – 75% of all players in their first season and 69%, 54% and 30% in subsequent seasons as players picked later renegotiate to bigger deals.


R^2 - Draft Value to Salary Value
Pos
Prior
Current
Next
C
0.2%
3.2%
1.0%
DB
0.8%
2.2%
6.9%
DE
5.5%
13.0%
1.2%
DT
0.4%
2.6%
9.3%
G
5.2%
0.1%
1.9%
LB
12.6%
40.7%
0.4%
QB
0.0%
0.1%
0.5%
RB
8.6%
20.1%
17.2%
T
0.1%
12.0%
1.2%
TE
0.1%
0.7%
1.6%
WR
16.7%
2.5%
1.2%
Average
4.6%
8.8%
3.9%
 

The first thing that stands out is that this is pretty weak overall. There are clearly more important factors affecting how much draft capital is spent on a given position than the collective amount spent on players at that position.

The other thing that I pick out of this table is that the current season is more significant than either the prior season or the following season.

Conclusions

It’s hardly definitive, but the implication is that teams are more influenced by the current layout of salaries in the league or are so bad at predicting that the correlations don’t reflect the attempt to be forward-looking.

An alternative explanation would be that these numbers are so small this is all just noise.

If anyone has other ideas of how to get at measuring this effect feel free to drop them in the comments. I’m certain there’s a better way to find it.



[1] 1996 through 2012 salary data

1 comment:

  1. Yeah, there is something, about what we can consider. Really, NFL does not have a reputation as a forward-thinking league. And it's sadly. But I hope, in the nearest fututre we'll see changes. Recently, I found this page about nfl betting http://sportsbetting-x.com/nfl-betting It's really interesting to read.

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