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Colin Kaeperick and Interceptable Passes: Unpacking a subjective metric

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Pre Snap Reads looks at the “interceptable passes” thrown by NFL quarterbacks. How much stock should you put in the metric?

Ed Szczepanski-USA TODAY Sports

Quantifying quarterback play is hard. The generally accepted quarterback rating doesn’t take things like drops into account. And it excludes rushing yards or scrambling ability alltogether.

Evaluating quarterback play necessitates subjective analysis. It’s with that in mind that Cian Fahey constructed The Interceptable Passes Project, an attempt to operationalize the number of interceptable passes a quarterback will throw over the course of a season.

Of course, I immediately looked to where Colin Kaepernick ranks on the list. The chart is a little difficult to read at first, but the basics are simple: The higher the QB on the list the more passes he throws before throwing a pass thats interceptable.

Colin Kaepernick throws an interceptable pass once every 21.7 throws, ranking him 19th out of 31 ranked QBs. The quarterbacks just above and below Kap? Drew Brees and Geno Smith, respectively. The quarterback at the top of the list? Alex Smith.

While the article is a great attempt at getting towards a proxy metric for decision making/execution, you should definitely take it with a grain of salt. Cian (correctly) points out that Alex Smith being at the top of the list is more a function of being overly safe than it is being a fantastic quarterback. And therein lies the rub with the article.

Subjective analyses are improved when you establish clear criteria for your observations. Your very first question when reading the title of the article should be "what defines an interceptable pass?" I asked Cian that question on Twitter, and didn’t really get a clear response.

Definitely read the entire back and forth, but in short, Cian kind of takes the "obscenity" route: I know it when I see it.

Even if you grant the ambiguous definition, I would prefer a QB to throw some interceptable passes as it shows risk-taking ability. Risk aversion means you don’t let your best players make a play; you continually take the safe route and end up limiting your scoring potential.

You also have to take the 49ers personnel into account. Anquan Boldin isn’t a burner, but his vises hands and ability to position himself mean that the window doesn’t need to be very large. How do you reconcile a completed pass thrown in a tight window where a defender can make a play but the receiver catches it anyway?

You shouldn’t discount the metric all together. Kap made some pretty terrible decisions last year. When he made the right decision, he sometimes didn’t execute the throw. While this analysis captures some of this, it’s a little too flawed for my taste.