Wednesday, April 27, 2011

Risk and Drafting a QB

What kind of football related blog would this be without some kind of post related to the upcoming NFL draft? It was not difficult to know that a post was necessary, finding an angle that has not been done to death by the football media that, outside of some truly exciting court rulings, has had nothing else to talk about recently.

After surveying the landscape, and seeing yet another discussion of how many first round busts there have been (particularly at the QB position) but no QB in current crop of potential first rounders being labeled as the potential bust, I thought I would take up the mantle of uncertainty in the NFL draft.

As a believer in on field performance above all else (pro day work outs, combine performances etc) I dug into the on field performances of all the QBs that received a draft grade of 2 or higher from Sports Illustrated in order to see which player's performance might have the highest probability of being a mirage. The most direct numerical way to look at this is to build the 95% confidence interval around a QB's completion percentage. Using a player's number of attempts with their completion percentage, I calculated a range of values for each QB's "true" completion percentage. The wider the range, the riskier the pick is.

Based on this admittedly crude measure we can see that Cam Newton has the highest level of uncertainty around his college completion percentage. In his career, Cam completed 65.4% of his passes, but due to the small sample of passes attempted, his "true" completion percentage is somewhere between 59.9% and 70.9%. This is a fairly wide range of potential values, which suggest that we likely do not have enough information to properly evaluate Cam at this point. To be clear, I do not mean that statisticians do not have enough information, but that talent evaluators of all types, do not have enough information to determine Cam's true level of performance.

Cam has the highest standard error in this group at +/- 5.5% while the standard error of the next highest QB to receive a draft grade higher than 3 is Ryan Mallet with a standard error of +/- 3.1%. This suggests that the evaluations of players like Mallett and Gabbert are more likely to be accurate that the evaluation of Newton. This is not to suggest that Cam will not be a successful NFL AB, but that NFL teams should be careful to factor in the high level of uncertainty when drafting him relative to the other highly regarded QBs.

Player  School  Grade Compl% High Low Std Err.
Cam Newton  Auburn  3.12 65.4% 70.9% 59.9% 5.5%
Jeff Van Camp  Florida Atlantic  2.14 57.2% 61.4% 53.0% 4.2%
Scott Tolzien  Wisconsin  2.26 68.1% 71.8% 64.4% 3.7%
Ryan Colburn  Fresno State  2.11 62.1% 65.8% 58.4% 3.7%
Greg McElroy  Alabama  2.34 66.3% 69.9% 62.7% 3.6%
Jordan La Secla  San Jose State  2.1 59.1% 62.7% 55.5% 3.6%
Tyrod Taylor  Virginia Tech  2.36 57.2% 60.5% 53.9% 3.3%
Ricky Stanzi  Iowa  2.5 59.8% 63.0% 56.6% 3.2%
Ryan Mallett  Arkansas  3.02 57.8% 60.9% 54.7% 3.1%
Blaine Gabbert  Missouri  3.14 60.9% 64.0% 57.8% 3.1%
Christian Ponder  Florida State  2.83 61.8% 64.9% 58.7% 3.1%
Ben Chappell  Indiana  2.27 61.1% 64.0% 58.2% 2.9%
Jerrod Johnson  Texas A&M  2.33 58.6% 61.5% 55.7% 2.9%
Jake Locker  Washington  2.92 53.9% 56.8% 51.0% 2.9%
Taylor Potts  Texas Tech  2.22 66.3% 69.1% 63.5% 2.8%
Colin Kaepernick  Nevada  2.9 58.2% 60.9% 55.5% 2.7%
TJ Yates  North Carolina  2.38 62.3% 65.0% 59.6% 2.7%
Andy Dalton  TCU  2.88 61.7% 64.3% 59.1% 2.6%
Nathan Enderle  Idaho  2.41 54.6% 57.2% 52.0% 2.6%

No comments:

Post a Comment