Staturday: Quantifying the NBA Draft

When we analyze player trades, a wealth of analytical tools is at our disposal. We can see how a player's efficiency fluctuated with his role on a team, how a player's rebounding fluctuated with better or worse rebounders at his side, how his defense held up against stronger or weaker opposition. As long as it's properly contextualized, player value can be effectively quantified.

But what happens when a player is traded for a draft pick- a nebulous concept of a future player who may or may not be good? Taking that a step further, what happens when a trade primarily involves only draft picks, as happened with New Orleans' swap of the 11th pick for the 21st and 26th selections? When the 11 for 21 and 26 was announced, many of us were disappointed that it wasn't 18 and 21. Can we quantify just how big of a drop off that was?

The NFL Draft Value chart entered mainstream popularity, probably around the mid 2000's. While many contend that its accuracy is limited today by new salary rules and rookie salary levels, it's still purportedly used by many NFL teams. For those who haven't seen it before, a version is reprinted after the jump.

Tradevaluechart_medium

Each slot is assigned a value, ranging from 3000 to 2. When trading picks, the values of the picks can then be referenced, added, subtracted, etc, in determining a "fair" or "unfair" trade. The original chart was devised by the Dallas Cowboys in the 1990, and while it's proven effective, I couldn't tell you more about the methodologies used to arrive at the values. However, this analysis done by Pro Football Reference in 2008 (based on empirical value at each pick since 1980) shows that the Cowboys' original chart is indeed quite accurate.

As the common phrase goes, it's a tool, not a rule. If a team needs quantity over quality in a particular draft, adherence to the chart can obviously vary. If a team hones in on a particular player that they have inside information on (see: New Orleans and Marcus Thornton, or San Antonio and Tony Parker or Manu Ginobili), the chart's values might not mean as much. But as an abstract tool, from a holistic year-to-year perspective, it can be very useful. 

My original idea was to find average NBA rookie production at each spot, effectively translating that chart to NBA terms. But, Pro Football Reference's cousin, Basketball Reference, has done that and more already. Their work certainly spares us some statistical leg work and lets us jump straight into evaluating the Hornets' trade.

From b-r, the expected win shares of NBA players in their first four seasons:

Here is the value chart for all of the draft picks:

+------+------+
| Pick | EV   |
+------+------+
|    1 | 26.5 |
|    2 | 22.1 |
|    3 | 19.6 |
|    4 | 17.8 |
|    5 | 16.4 |
|    6 | 15.2 |
|    7 | 14.2 |
|    8 | 13.4 |
|    9 | 12.7 |
|   10 | 12.0 |
|   11 | 11.4 |
|   12 | 10.8 |
|   13 | 10.3 |
|   14 |  9.9 |
|   15 |  9.4 |
|   16 |  9.0 |
|   17 |  8.7 |
|   18 |  8.3 |
|   19 |  8.0 |
|   20 |  7.6 |
|   21 |  7.3 |
|   22 |  7.0 |
|   23 |  6.7 |
|   24 |  6.5 |
|   25 |  6.2 |
|   26 |  6.0 |
|   27 |  5.7 |
|   28 |  5.5 |
|   29 |  5.3 |
|   30 |  5.1 |
|   31 |  4.9 |
|   32 |  4.7 |
|   33 |  4.5 |
|   34 |  4.3 |
|   35 |  4.1 |
|   36 |  3.9 |
|   37 |  3.8 |
|   38 |  3.6 |
|   39 |  3.4 |
|   40 |  3.3 |
|   41 |  3.1 |
|   42 |  3.0 |
|   43 |  2.8 |
|   44 |  2.7 |
|   45 |  2.5 |
|   46 |  2.4 |
|   47 |  2.2 |
|   48 |  2.1 |
|   49 |  2.0 |
|   50 |  1.9 |
|   51 |  1.7 |
|   52 |  1.6 |
|   53 |  1.5 |
|   54 |  1.4 |
|   55 |  1.3 |
|   56 |  1.1 |
|   57 |  1.0 |
|   58 |  0.9 |
|   59 |  0.8 |
|   60 |  0.7 |
+------+------+

 

This is the result of a logarithmic function, rather than the average values at each position themselves, to iron out abnormalities in data (ie, one pick inexplicably having very bad players every draft). 

I've bolded the 11th, 18th, 21st, and 26th selections. Time for the exceedingly simple math. The 18th pick and the 21st pick together provide an average of 15.6 win shares in a player's first four years. That's a clear upgrade from the eleventh pick's 11.4 value and helps explain why our gut feeling at the 11 for 18+21 trade was immediately positive. The 21st and 26th selections add up to 13.3 win shares, again beating just the eleventh pick by about 2 wins. 

Before Brackins or Pondexter or anyone was drafted, at the moment the trade was made, it was already a shrewd one. I'll say for the tenth time, none of the values on this chart should be taken as gospel. But the historical values of the 11th, 21st, and 26th picks indicate that Jeff Bower and the front office had a good idea of what they were doing. Add in OKC taking Mo's contract, and it's fairly obvious who came out on top in this deal. 

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