In this week's Varsity Numbers, Bill Connelly takes a page out of baseball's playbook and attempts to isolate power from efficiency.
25 Jul 2007
by Aaron Schatz
On Monday, we delved into the Football Outsiders game charting data to look at which quarterbacks saw their completion percentages suffer due to dropped passes, and which quarterbacks saw their completion percentages get better or worse because they happened to throw more short or long passes.
Today, we want to look some more at incomplete passes from the 2006 season, and the various reasons why passes were incomplete.
|Percent of Passes Marked Overthrown/Thrown Ahead|
|Most Overthrows||Fewest Overthrows|
"Overthrown" refers to passes thrown over the receivers head, while "Thrown Ahead" refers to passes thrown in front of where the receiver is running his route (for example, thrown out of the receiver's reach on a crossing pattern). Overthrown passes were about four times as common, and these are pretty similar errors, so we combined them for this table. Obviously, an overthrown pass is not necessarily the fault of the quarterback. Perhaps the receiver was jammed at the line, or ran a route slightly wrong, or just wasn't fast enough to get where he was supposed to be.
Not every quarterback with a lot of Overthrown passes also had a lot of Thrown Ahead passes, and vice versa. For example, Marc Bulger and Tom Brady had the most Thrown Ahead passes in the league, but both had an average number of Overthrown passes. Actually, the stats on the Rams' incomplete passes are generally weird. Torry Holt was overthrown on 27 passes, the most in the league and two-thirds of all of Bulger's overthrows. Isaac Bruce was only overthrown six times, but he was the target on eight "Thrown Ahead" passes, the most in the league. No other Rams receiver was the intended target on more than two "Thrown Ahead" passes, and that includes Holt.
Some quarterbacks had general problems overthrowing their receivers. Brett Favre's overthrown passes were equally split between Donald Driver and Greg Jennings, with a few left over for everybody else. Jake Delhomme overthrew both Steve Smith and Keyshawn Johnson equally. Other quarterbacks had specific issues with specific receivers, primarily those who ran deep routes. Most of Grossman's overthrows were to Bernard Berrian or Rashied Davis. Most of Harrington's overthrows were to Chris Chambers. Most of Eli Manning's overthrows were to ... well, actually, a lot of them were to Plaxico Burress, but there were also a good number of overthrows intended for Jeremy Shockey.
|Percent of Passes Marked Underthrown/Thrown Behind|
|Most Underthrows||Fewest Underthrows|
Again, we've combined two different but similar categories here. "Underthrown" passes didn't get far enough vertically down the field, while "Thrown Behind" passes were behind the receiver as he was running left or right. The total number of passes marked as "Underthrown" was less than half the total number of passes marked as "Overthrown." Both "Thrown Behind" and "Thrown Ahead" were each about 30 percent as common as "Overthrown."
The most frequently underthrown receivers in the league were -- surprise -- two speed merchants. Chris Chambers had 14 underthrown passes, Joey Galloway had 13, and nobody else had more than eight. The two receivers with the most "Thrown Behind" passes were Donald Driver and Roy Williams, although they weren't far ahead of the rest of the league in the same way.
Matt Leinart had twice as many "Thrown Behind" passes compared to "Underthrown" passes. The only other quarterbacks to have more "Thrown Behind" passes than "Underthrown" passes (minimum 100 passes) were Jake Plummer, Aaron Brooks, and Seneca Wallace.
Now here's the big table, combining all four of these "poor accuracy" categories.
|Percent of "Bad Passes"|
|Most Bad Passes||Fewest Bad Passes|
The list of the quarterbacks with the most bad passes doesn't really have any surprises on it. As far as the list of the quarterbacks with the fewest bad passes, Charlie Frye and David Carr learned last year that it is hard to be inaccurate when every pass only has to go three yards, and that doesn't necessarily make you a good quarterback. The presence of Andrew Walter and Aaron Brooks on this list makes the Oakland offensive line look even worse than they looked before, because those guys weren't half bad when they actually managed to get a throw off.
The strangest result on this table, however, is Byron Leftwich coming out with a high number of bad passes, and David Garrard coming out with a low number. It could simply be the effect of which game charters did which games. There's also nothing to say that throwing a pass that falls incomplete because it was defensed is any better than throwing a pass that falls incomplete because you overthrow the receiver.
Check out this comparison of incomplete passes by Leftwich and Garrard:
|Hit in Motion/Tipped at Line||11||8|
That is certainly different than what I would have expected to see, and it makes me wonder if I am correct in supporting Leftwich over Garrard as Jacksonville's starting quarterback. Then again, half a season for each player isn't the kind of sample size that anyone should be making decisions on.
Here's a look at which quarterbacks had the highest and lowest percentage of passes marked as Pass Defensed:
|Most Passes Defensed||Fewest Passes Defensed|
Looking at that list of quarterbacks with the highest percentage of incompletes marked "passes defensed," I would say that there definitely is something to the idea that having more passes defensed than passes overthrown and underthrown does not necessarily say good things about David Garrard's quarterbacking ability. You want your quarterback to be accurate, but you also don't want him throwing into coverage. A quarterback who has a lot of passes defensed is a quarterback who threw into coverage too often.
This leaves three other reasons for incompletes. First, pass interference or illegal contact, which of course actually end up with yardage for the offense. Second, the random assorted stuff like Receiver Tripped, Ball Hit Umpire, and Hail Mary. Third, the reasons related to the pass rush: Thrown Away, Hit in Motion, and Tipped at Line. Combining those three categories, here are the quarterbacks who most often had incomplete passes specifically due to the pass rush:
|Hit in Motion/Tipped at Line/Thrown Away|
No, I don't have any clue how Andrew Walter ended up on the bottom of this list either. The guy certainly took enough sacks, didn't he? Most of the quarterbacks on the bottom of the list are guys who didn't have throws affected by the pass rush because they were good at avoiding it, but Walter and Culter are guys who didn't have throws affected by the pass rush because the pass rush usually ended the play sitting on top of them, possibly with the ball popping out and into a defender's hands.
What happens if we remove Thrown Away, and only include Hit in Motion and Tipped at Line? Most players stay in roughly the same place, with a couple of huge exceptions: Drew Bledsoe and Mark Brunell go from the top of this list to the bottom. Say what you will about Bledsoe and the pass rush, but that's two veterans who know that sometimes you just need to throw the ball away.
Let's look at one more list: Passes Thrown Away divided by Passes Thrown Away plus sacks. In other words, which quarterbacks were the best at getting rid of the ball before they went down?
|Thrown Away as a Percentage of
(Thrown Away + Sacks)
|Most Thrown Away||Most Sacks|
Thanks again to Bill Moore for putting most of these tables together and coordinating the whole game charting project. Just like last year, we've now made the game charting data available for anyone who wants to purchase it and do their own studies. The 2006 data costs $60 and please make sure that you read the whole legal agreement before purchasing.
74 comments, Last at 17 Aug 2007, 6:37pm by stan