Thursday, April 18, 2013

Leave the running back, take the quarterback (or center, or tackle)

For a number of reasons, drafting NFL players is a crapshoot. There are a wide variety of ways for a team to end up getting less than they bargained for – and less than the draft slot could have provided. A player could have a career ending injury before they even hit the field or they could even turn out to be not very good. I can’t help with those things.

What I can help with, however, is the third way a team could end up with a sub-optimal choice in the draft: ignorance of positional value.

Looking back over the past 19 drafts and using career value in terms of % of the salary cap, we can rank the actual value delivered and compare it to the draft slot where the player was selected. For example, Tim Couch was selected first overall by the Cleveland Browns in 1999 and delivered a career value of 18% (units are % of the salary cap to normalize across seasons). The actual most valuable player to date from that draft is Donovan McNabb with a career value of 98%. By those two numbers, Tim Couch’s selection would be rated as an unfavorable error of 80%. McNabb was drafted second and outperformed the actual second most valuable player in the draft (Champ Bailey with 76%) so he gets a favorable error of 22%.

Why should teams keep taking quarterbacks early?

Outcome of first round picks since 1994
Because that’s where the money is! Wait, that’s why people rob banks. Being by far the most valuable position on the field, QB is the position where even an average starter can justify the expectations of a first round pick. A starter at QB is worth the same as a pro bowl-caliber running back. Speaking of running backs, they perform… not well at this metric. Combining the tendency to outright disappoint and the tendency toward short careers leaves teams with an asset that underperforms the expectation for the draft slot.

What to do with the rest?

Note first of all that all errors here are negative. Because these are first round picks and this method is a zero sum game, if any fail to end up in the top 32 of their draft’s actual value they will result in a negative (unfavorable) error. While individual picks can be positive – if the player drafted 4th turns out to be the 2nd best in reality – the effect of 2nd-7th rounders outperforming drags down the first round numbers.

QBs may be roughly split between those two underperform and those who either meet expectations (the best you can do at the first pick) or exceed them, but they have a huge standard deviation that speaks to the boom or bust nature of high QB picks. Players like Tim Couch, Akili Smith and Cade McNown highlight the risks – and that’s just from the 1999 first round.

Offensive linemen turn out to be the most reliable bets in the first round, with relatively low errors and standard deviations. Receivers and running backs, on the other hand, represent the highest errors but have a glimmer of hope in their standard deviations. Despite the average error there are still numerous examples of receivers and running backs who work out in the league.

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