In this week's Varsity Numbers, Bill Connelly takes a page out of baseball's playbook and attempts to isolate power from efficiency.
26 Aug 2005
Guest Column by Kevin Pelton
The Seahawks infamously finished second in the NFL in drops in 2003, a surprise for a talented unit that boasted Darrell Jackson (who signed a lucrative new deal after the season), former top-ten pick Koren Robinson, and Football Outsiders favorite Bobby Engram. The problems were written off to focus and confidence issues and a host of other excuses.
But 2004 came and went, and the problem continued. Jackson tied for second in the league in drops, and Robinson would have topped him had he not been so busy getting suspended. The situation culminated in the usually reliable Engram dropping a pass in the end zone that would have sent the Seahawks' Wild Card playoff loss against the St. Louis Rams into overtime.
The jokes came fast and furious, with Tuesday Morning Quarterback replacing "Blue Man Group" as the Seahawks' nickname with first "Dropped Passes Group" and later "Folgers -- good to the last drop."
Lost in all the attention paid to the drops was the fact that the Seattle secondary allowed St. Louis to throw for 313 yards and a pair of touchdowns in the playoff loss.
Was too much made of the Seahawks drops? It seems a fair question to ask. By Football Outsiders' advanced metrics, the Seahawks finished with the NFL's third-best offense in 2003 and were 13th even in a down 2004, so it's not as though the drops rendered the offense ineffective.
The problem with focusing on drops in a statistical sense is that they are merely a visible failure on the part of the receiver. By contrast, no stats are kept on times the receiver misjudges the ball and doesn't catch it or doesn't get open in the first place.
A rough analogy I've long had in my head compares drops to strikeouts for hitters in baseball. Conventional wisdom long held that hitters who struck out frequently were not valuable, but statistical analysis has demonstrated that strikeouts are not substantially different than groundouts or flyouts.
What do the numbers say in football? With the help of the FO data, I set out to investigate.
The first step is to evaluate exactly who drops the ball most frequently. Drops aren't an official stat, but they're tracked by STATS, Inc. (Of course, there's no way to get the data without clicking on every single wide receiver's individual page, and drops are not listed for tight ends and running backs unless they are in the league's top 20 overall.) Their 2004 leaderboard (for wide receivers only) looks like this:
|2004 Drops Leaders|
Bad Seahawks memories flooding back ... Anyways, this is a pretty misleading when you consider Chad Johnson was targeted for 169 passes, Az Hakim just 57. A better way to evaluate drops is in terms of percentage of targeted passes. Doing so gives us the benefit of better being able to sort out the best players. I've calculated "drop percentage" for every receiver with at least 50 targeted passes last season, and here are the best and worst in terms of hanging on to the ball:
|Highest Drop Percentage, Top 5|
|*Bryant's stats are from Cleveland only|
|Lowest Drop Percentage, Top 5|
In a result that is no shock for those not named Matt Millen, Hakim was the league's most frequent dropper last season. The much-maligned Robinson ranks second, followed by a pair of players who were not on the first list.
At the other end, Deion Branch -- who also caught 68.6% of passes thrown to him last season to rank fifth in the league -- is certifiably the NFL's most sure-handed player.
It's worth noting that Johnson and Jackson, one-two in the league in total drops, ranked 10th and 16th in the NFL, respectively, in drop percentage.
As a first cut at looking at how important drop percentage is, I compared it to players' catch percentage to see how well it reflects all passes not caught by the receiver, whether "catchable" in STATS' opinion or not. The correlation coefficient between the drop percentage and catch percentage is -.229, indicating that players who drop the ball more frequently tend to catch fewer passes. The relationship, however, is not particularly strong. Recall that a correlation coefficient near zero indicates no correlation, while a value close to 1 or -1 indicates strong correlation.
Perhaps this makes more sense graphically, so take a look at the chart at right which compares drop percentage and catch percentage.
On the other hand, if you look at the top and bottom five lists, the players who drop the ball least often average a 63.2% catch percentage, as opposed to 53.7% for the frequent droppers. That's a pretty significant difference.
Presumably, players like Hakim and Robinson are playing despite questionable hands because of the difficulty their speed presents for opposing defenses. Because of this, it makes sense to look at how well drop percentage correlates with overall receiver performance, as measured by DVOA. (DVOA explained here.) In this case, the correlation coefficient is even lower (-0.055), which indicates almost no relationship whatsoever.
The corresponding chart shows how weak the relationship is; the receivers are distributed in something approximating the circle familiar to anyone who's taken a statistics class as an example of variables with no relationship.
It's also interesting to note the regression line on the chart, which indicates even if there was a relationship, it wouldn't mean much. The difference in projected DVOA between Hakim and Branch, based on their drops, is less than 10%. (Oddly, both players were dramatically better than their projection. That means something, but I'm not sure what.)
The last test is to look at drops at the team level. The Seahawks (7.1%) did finish second behind the Jacksonville Jaguars (8.2%) in team drop percentage last season. Why didn't the Jaguars' drops get more attention, you ask? Probably because the team wasn't that good -- but also because nearly a quarter of Jacksonville's drops came from running back Fred Taylor, who's not expected to be as sure-handed as a receiver. (Taylor's drop rate would, to go on a tangent of a tangent, rank second only to Hakim were he a wide receiver.)
The NFL's top three passing teams -- Indianapolis, New England, and Minnesota -- ranked first, second and fifth in lowest team drop percentage. Between them, however, were Tampa Bay (1.7% passing DVOA) and Arizona (-22.4%), while fourth-rated Kansas City was fifth in highest team drop percentage. The league's worst passing team, Chicago, was above-average in avoiding drops.
Again, there's a relationship, but it's a weak one (-0.225).
After looking at the data, I don't think my original analogy is accurate. There is clearly some harm in dropped passes. A better baseball analogy -- at the risk of forcing it -- appears to be errors. Like errors in baseball, dropped passes are harmful, but they're relatively infrequent, making them less important than other factors (as range tends to be more important in baseball). Also, like errors, drops tend to be more visible than these other mistakes, making them stand out to the hecklers in the stands and causing them to be overrated.
Lastly, what of my Seahawks this season? The statistics indicate improvement is likely. Seattle replaced the biggest offender, Robinson. Combined, the Seahawks' two new receivers (Jerome Pathon and Joe Jurevicius) and Engram, who will be asked to step up, dropped only four passes in 156 targets last season. (Jurevicius did not have a single drop in 37 targets.) If all goes as planned, by midseason we should be back to TMQ having only the Seahawks' garish monochrome home jerseys to pick on.
Kevin Pelton is a basketball writer by trade who is employed by the Seattle SuperSonics. His work appears on SUPERSONICS.COM and storm.wnba.com. He frequently dropped passes in flag football at the University of Washington. If you are interested in writing a guest column for Football Outsiders, something that takes an unconventional look at the NFL, drop us a line at info-at-footballoutsiders.com.
Seattle fans: Make sure you also check out our thoughts on your team in Four Downs: NFC West from earlier this week, and listen to FO editor-in-chief Aaron Schatz tonight at 8:05pm Pacific on Sports Radio 950 KJR.
31 comments, Last at 05 Sep 2005, 12:48am by Kevin Pelton