A Review of the NFL's Guidelines for Individual Defensive Statistics

  Posted 8/6 by Jene Bramel, Exclusive to Footballguys.com

Tackles, both solo and assisted, and passes defensed are considered unofficial statistics by the NFL. Though each statistic shows how often an individual defender succeeds at a critical skill, the records are unofficial with good reason. The speed and meet at the ball gang tackling mentality often make awarding defensive stats a judgment call. Not surprisingly, differences in judgment among each team's individual stat crews have led to significant discrepancies in how tackles and passes defensed have been recorded.

Fellow FBG Aaron Rudnicki has tracked those anomalies since 2005. He noted some very interesting differences in looking for ways to exploit the differences in IDP leagues. Briefly, two of his more notable findings included:

• The Philadelphia stat crew was generous to the point of absurdity in awarding passes defensed. In 2005 and 2006, Eagle defensive backs were awarded three times as many PDs in their home stadium than on the road. Football Outsiders published similar findings.
• Stat crews in Cincinnati, Cleveland, Pittsburgh, Miami, New England and Buffalo were significantly more likely to award assisted tackles than those in St. Louis, Atlanta and Jacksonville.

Early in the 2007 season, however, it became apparent that the league was more consistently recording assisted tackles and passes defensed, awarding both stats less often. The Philadelphia stat crew was no longer awarding passes defensed to their defensive backs in bushels. Miami defenders were being awarded fewer assisted tackles. After the season ended, a closer look at how teams were awarding assisted and passes defensed suggested that the league had made a concerted effort to bring some uniformity to their recording of unofficial defensive statistics.

Consider the following table looking at the passes defensed stat over the past five seasons:

Passes Defensed Awarded by NFL 2003-2007*

*All statistics tabulated using FBG Data Dominator

Between 2003 and 2006, the NFL stat crews awarded an average of 2581 passes defensed per season. Last year, the crews awarded only 2371 passes defensed, a drop of over 200 from the prior four season average. That's a decrease of 8.15%. The Philadelphia Eagles, after leading the league in passes defensed in 2005 and 2006, had the second fewest number of total passes defensed in 2007 with 75, fourteen less than the league average and well below the nearly 200 their defenders had been awarded in previous seasons.

The numbers were just as dramatic for assisted tackles.

Assisted Tackles Awarded by NFL 2004-2007*

*All statistics tabulated using FBG Data Dominator

Between 2004 and 2006, the NFL stat crews awarded an average of 7789 assisted tackles per season and nearly 8000 in 2006. Last year, the crews awarded only 7068 assisted tackles, a drop of 721 from the prior three season average and nearly 1000 assisted tackles less than in 2006. That's a decrease of 9.26% from the prior three season average. The Miami Dolphins, as noted above, were awarded 144 fewer assisted tackles last year, a decrease of nearly 40% from 2006. The St. Louis Rams were awarded 48 more assisted tackles in 2007, an increase of over 50% from the year prior. While those numbers aren't controlled for home and away changes, the differences are striking.

Neither the decrease in passes defensed nor assisted tackles were related to a decrease in plays from scrimmage. In fact, while it's not significant on a percentage basis, there were more plays from scrimmage than in any of the past three seasons. Clearly something had happened between the 2006 and 2007 seasons.

After a friendly exchange with those tasked with setting the standards for the league's statisticians, we were able to confirm that the league had indeed sent more detailed instructions to its stadium crews. Whereas the statisticians previously had operated under a wide open "you'll know a tackle when you see it" guideline, the NFL put together a 25 minute video to aid the stat crews in improving the uniformity and consistency of the league's tackle and pass defensed statistics. Thanks to the NFL's Chris Hoeltge, we were able to watch that video and summarize its content.

The overarching guideline for all defensive statistics, including the official sack statistic, is now to credit only those defensive players who had a material effect on the outcome of the play. With that principle in mind, the NFL attempted to clarify the situations that are most often subject to judgment calls by the lead statistician and his crew.

Out of Bounds Plays

• Award solo tackle if the defender contacts the ballcarrier before he steps out of bounds.
• Award solo tackle if the ballcarrier steps out of bounds to avoid imminent contact with defender.
• Do not award solo tackle if the ballcarrier's momentum carries him out of bounds before defender arrives.
• Do not award solo tackle when a ballcarrier runs out of bounds specifically to stop the clock.

Assisted Tackles

• Award assisted tackle if second defender materially shortens the duration of the play.
• Award two assisted tackles (and no solo tackle) if the ballcarrier is hit simultaneously by two defenders.
• Award two assisted tackles (and no solo tackle) if the first defender is unable to complete the tackle on himself. This guideline will often be used in an "in the grasp" situation or a shared sack.
• Do not award assisted tackle if ballcarrier would have been successfully tackled without contact from a second defender. Players who pile on when a tackle has already been made should not be awarded an assisted tackle.
• Do not award assisted (or solo) tackle if ballcarrier completely escapes the initial contact.
• Do not award assisted tackles on quarterback slides.

Passes Defensed

• An interception is a pass defensed (corollary to a sack is a solo tackle, half-sack is an assisted tackle).
• Award a pass defensed if a defender bats down a catchable ball.
• Award a pass defensed if a defender bats a ball down at the line of scrimmage while playing the pass.
• Award a pass defensed if a defender jars the ball loose and prevents a reception.
• Do not award a pass defensed if a ball is uncatchable, including situations where a ball is caught but the receiver is deemed out of bounds.
• Do not award a pass defensed if a pass rusher inadvertently causes an incomplete pass in the process of rushing the passer.
• Two passes defensed may be awarded if a pass is deflected by one defender then intercepted by a different defender.

The clarifications may not be groundbreaking changes, but they remove much of the wide latitude inherent in the "you'll know a tackle when you see it" framework. Thus far, the more specific guidelines outlined in the video have had the desired effect. It will be interesting to see whether the trend continues in 2008.

As always, questions, comments, suggestions and corrections are welcome by e-mail at bramel@footballguys.com.