30 Jun 2009
While doing research for our upcoming book, I started to look into solving a problem that's been on my mind ever since my first article for Football Outsiders, the "Four Downs" in which I first started analyzing Chris Chambers and his low catch rate; namely, adjusting a player's catch rate for the distance and location of the throw, as well as the situation the throw came in.
The idea, of course, is to create a purer "Hands" metric that measures a player's ability to catch the ball versus something approaching a league-average receiver.
The bad news is that the research didn't pan out; after adjusting for various situations and running a simple regression, the best hands in the league belong to ... Ike Hilliard. That's too close to my "Horizontal Yards" parody for comfort, so I'm going to shelve the system for now. (The worst hands on a per-play basis, by the way, were Ashley Lelie's.)
As part of doing the research, though, I came across an interesting side note that I thought was worth bringing up as an XP. One of the variables I was accounting for in my analysis was the number of yards between the location where the pass was caught (or ruled to be incomplete) and the first down marker; it was an attempt to adjust for players getting easy catches eight or nine yards down the field on third-and-12 or second-and-20. (Keep in mind that this analysis strictly considers the yardage in the air of passes, not any yards after catch.)
In looking at completion percentage by yardage totals relative to the first down marker, I found a very interesting trend. Take a look at the 2008 completion percentage of passes thrown to within two yards of the marker on third downs:
|Down||v. ToGo||Cmp %|
That's right -- it's about 20 percent harder to complete passes at the marker than it is to complete them within two yards on either side of the marker.
Now, this would seem to make sense -- defenses know that the offense is looking for the sticks on third down, so they're comfortable dropping their linebackers or even their corners right at the first down marker. What if we look at first or second down?
|Down||v. ToGo||Cmp %|
Although the effect isn't as pronounced, it's still there; it appears that teams simply are better off going past the yellow line if they want to move it.
I say "appears" because the possibility exists, naturally, that this could be a mathematical fluke, a small sample, or a reporting issue (maybe official scorers and/or our charters are inherently more likely to report a pass going just beyond or before the sticks for some reason). We're looking at samples of several hundred passes for each "yard" being measured, though, so there appears to be a legitimate effect in play.
Are teams accounting for this in their offense? Hard to say. In 2008, the offense that threw the highest percentage of its passes to the sticks was Kansas City, at 9.6 percent; other offenses above eight percent included the Giants (8.7 percent), Indianapolis (8.4 percent), San Francisco (8.6 percent), and Jacksonville (8.1 percent). If we look strictly at third down, Houston threw 15 percent of its passes right at the yellow line, followed by Kansas City (14.9 percent) and both Indianapolis and New England (14.0 percent).
On the flip side, Tennessee stayed away from the zero-yard line; only 4.3 percent of its third down passes and 4.7 percent of its total were at the sticks, both league-lows. Dallas (4.6 percent) and Baltimore (4.8 percent) were the only other teams below five percent on third down, while those teams, Minnesota, Cincinnati, St. Louis, and Pittsburgh were all below six percent overall.
I'm interested in hearing your thoughts on why this effect might exist in the comments.
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