March 21, 2018

Rule of Thumb: The 60% Solution?

Checking an Old Rule of Thumb about College QBs

A guest spot by Eric Kennedy 

As an acknowledged NFL Draft junkie who spends weeks every winter immersed in video clips and scouting reports on college prospects, I’d often heard – and subscribed to – the rule of thumb that 60% was the minimum acceptable completion rate for a college QB to be considered a realistic NFL prospect. One day, I realized I’d never actually verified the accuracy of that Rule of Thumb; it seems reasonable, but is it really true?

So I undertook an effort to compare the college and pro statistics for all of the quarterbacks drafted in the years 2003 through 2012. The idea was to compare each player’s college and NFL key statistics to test the 60% Rule of Thumb. Along the way, I learned some interesting things about the players many now consider to be “elite” quarterbacks.

To make sure each player had sufficient NFL stats to make the comparison valid, I arbitrarily set a minimum of 10 NFL games played as the cutoff point on whether the player was considered part of the data set. This yielded 64 players for the years studied. I then added five more current or former NFL starters to round out the data, three of whom many consider to be “elite”: Drew Brees, Peyton Manning, Tom Brady, Michael Vick and Tony Romo.

First, I summarized the Completion Percentages for all the quarterbacks studied:




Indeed, the data suggests that the old Rule of Thumb is correct, as only four (4) of all the quarterbacks studied – a paltry 6% – had a college completion rate of less than 60% and went on to be “good” or “elite” NFL quarterbacks. None of the “elite” QBs had a completion rate that low in college. Interestingly enough, the “elite” quarterbacks actually improved their completion rate in the NFL compared to their college performance. This is contrary to what I personally had presumed.

Next, I looked at another key metric, Yards per Attempt (YPA), and did a similar comparison:






As you might suspect, the YPA for most quarterbacks (more than 84%) drops in the NFL compared to their college performance. The data suggest “elite” or “good” NFL quarterbacks will average 8.0 YPA in college; however, those quarterbacks that go on to be “elite” suffer very little drop off in YPA in the pros. All the other quarterbacks lose about a yard in YPA in their professional career.

Finally, touchdown to interception ratio (TD/INT) was summarized for the data set:







This set of data offers little for us draft junkies to use in projecting college quarterbacks to the NFL, although it does suggest that a TD/INT ratio of around 2.5 or higher in college may be an appropriate expectation for a player to project to “good” or “elite” status in the NFL. It is notable, though, that (on average) the “elite” NFL quarterbacks virtually match their college TD/INT ratio in the NFL.

So what does all of the above really mean? Certainly, the 60% Rule of Thumb seems to have been proved out, as only a very small percentage of drafted quarterbacks in the data set that had a college completion rate of less than 60% turned out to be any good in the NFL.

The other conclusion that comes out of the data is that players that go on to be “elite” in the NFL will virtually match – or improve on – their college statistics.

With today’s modern college offenses that spread the field and encourage short, high-percentage throws, it’s harder than ever to project college QB statistics to the NFL. But it turns out the old “60%” rule still holds up; if you draft a college QB with less than a 60% Completion Rate, then Buyer Beware.



One Response to “Rule of Thumb: The 60% Solution?”
  1. James Rowland says:

    Hmmm… Case Keenum 69.3%. That is all.

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