Correlations of salary expenditure by position to team regular season wins

Now, clearly a player's ability is the foremost factor in a team's personnel decisions, and depth at the position, replacability costs, alignment with the coaching game plan objectives, and many other factors all weigh into the equation.

However, stepping back for a moment, a simple way to begin exploring the subject of optimal salary distribution is to look at the correlations -- if any -- between salary expenditure by position with the wins a team accrues in a given season. In other words, at what positions is the money well spent?

For this first pass we have elected to use a three year database (2000 to 2002), and the positions are broken out into 12 classes: QB, RB, WR, TE, OL, DE, DT, LB, CB, S, K, P. Now there are additionally many ways to consider the salary implications of a player, including base salary, total salary, signing bonuses, but we have decided to go with the 'Cap Value' figure.

It certainly would be possible to correlate actual dollars spent versus wins, but given that the market should have some balances, what seems more important is the relative rank of spending by position (eg Team A has the highest amount of money allocated to Quarterbacks, therefore they rank #1 in QB cap value budgeting).

With these assumptions then, we can go to the simple individual correlation results:

Now before the Defensive Tackle Players Union gets up in arms about the above, let us issue the disclaimer that three years isn't a whole heck of a lot of data. It will be interesting to see how consistent these stats are when we retest against some more seasons.

Basically in terms of interpreting the correlation results, the higher the correlation the more related the team wins are to the salary spending at that position. So, amazingly the most valued position in this sample is the Kicker! Ludicrous some would say, although if you have read the brilliant account of Mike Vanderjagt's heroics in Denver on the Jeff Johnson's NFL Picks page (scroll down to week 13 of last season), you might think that indeed kickers have a pretty vital part to play. Furthermore, the cost difference between a top of the line NFL boot-swinger and an 'el cheapo' special picked up midseason is peanuts on the NFL scale.

Still, it must come as a shock to most to find how little correlation there is between Quarterback salary cap value spending and actual team wins. Of course we're not judging whether the money spent is advisable or even fair market value, and so it's just the cold facts that for instance puts two of the top four QB spending teams in 2002 as Jacksonville (6-10) and Arizona (5-11).

None of the correlations by position are all that strong, with only the Kicker, Running Back, and Cornerback slots showing noteworthy values, with Tight Ends and Defensive Ends knocking on the door. Before we jump into the whole hog "multiple regression" stage of this study, where we will look at several positions at once in assessing their relative merits to an NFL bean counter, we'll take another look at the individual units, this time assessing how well salary spending by position predicts offensive/defensive rankings.

So on offense Running Backs edge out Kickers for best correlation of position spending to team points scored. Tight Ends also show some modest relationship between spending and points. The show-stopper positions however show minimal significance.

For points allowed it turns out that Defensive Linemen are the top salary correlators, with cornbacks in the second spot (although CB's correlated better with team wins). Amusingly enough, punter salary expenditure has absolutely zero to do with the number of points allowed if you want to take the numbers literally.

The big question to consider is --

What does it all mean?

Thus when we talk about the relationship between a team's spending on a position and the gains for the team from this, we may be reflecting as much the "risk" of signing big money players at a position rather than the actual effect of that position on football outcomes.

This would explain why 'known commodities' like kickers show up well in our analysis above -- kickers tend to be reasonably consistent, and so when a team spends a little extra on the position they usually get what they paid for. On the other hand, there are many high profile Quarterback busts, particularly the hotshot first round draft picks out of college who suck up big money from a team's salary cap. Consequently a team with a lot of QB dollars budgeted may in fact be taking high risk with these contracts in that the players are likely not to deliver to the level of their salary.

Also as we mentioned, a three year sample is not conclusive by any means, particularly since the years are not independent -- an underperforming player with a multi-year contract will stay on the books throughout the sample, while on the flip side, an unsung hero who gets the job done at a lesser salary may not come round for a raise right away.

In general though, the initial conclusions are it's better to sink money into Running Backs, Cornerbacks, Defensive Ends and Tight Ends, and don't be skimping on a kicker!

See Also:
Correlation of highest paid player by position to team wins