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# Colin Kaepernick, the 49ers and ANY/A Differential

We introduce a new passing game stat and take a look at how Colin Kaepernick and the San Francisco 49ers defense stack up.

The favorite passing stat of many in the advanced stat world is adjusted net yards per attempt, or ANY/A.

Despite this, there does not exist on the internet (to my knowledge) any database of single game ANY/A, or, more interestingly, ANY/A differential and its correlation with winning football games. You can get yards per attempt differential correlated with wins, or passer rating differential -- but not ANY/A differential.

I took both challenges on in my spare time this past week to bring you such data today. And as the season rolls forward, I will continue to look back into seasons past to both establish a database of single game ANY/As and also see what use ANY/A might serve as a predictive tool.

To start, the first 4 weeks' worth of ANY/A has been calculated for every game. In case you are unaware of the formula, it goes as follows:

passing yards + (TDs * 20) - (INTs * 45) - sack yards
----------------------------------------------------------------------------------
pass attempts + sacks

Later today, an article of mine will be appearing on advancedNFLstats.com briefly introducing the ANY/A differential statistic, discussing it in a bit more detail, and talking about some match-ups you will see this Sunday.

The relevant thing for us is that the statistic is correlated with offensive point differential at 0.83 -- which is very high. Offensive point differential is simply how many offensive points you score compared to the other team. This means all points scored other than defensive and special teams touchdowns.

Put simply, recording a higher ANY/A than your opponent means putting more points on the board, too. Which, of course, equals wins.

Included in the article, is the following snippet on 49ers quarterback Colin Kaepernick:

Colin Kaepernick's roller-coaster ride continues

San Francicso's burgeoning young star, Colin Kaepernick, posted the 7th highest single game ANY/A of the year so far in his first bout against Green Bay at 11.32. He followed that up with a Blaine Gabbert-esque negative 0.90 in Seattle. Indeed, only Kaepernick and Gabbert have recorded negative ANY/A games in 2013.

For the following two weeks, the cycle of variance continued: Kaepernick had trouble against the Colts (3.13) in Week 3, but bounced back 4 days later verse St. Louis (7.64).

So as to which kid will show up tomorrow is anyone's guess, and probably only something Jim Harbaugh and Offensive Coordinator Greg Roman can control. The Houston defense ranks 9th in defensive ANY/A and has 13 sacks on the year, but they are giving up over 110 yards on the ground per game. A heavy dose of Frank Gore worked last week against St. Louis, and the team might be wise to stay the course.

For all the ANY/A statistics mentioned above and below, as well as a chart of team rankings for the season so far, travel to this Google Document containing the relevant spreadsheets.

Here are more Niner-related tidbits.

The 49ers rank 17th in ANY/A Differential through 4 games. This is due to a not-so-good 23rd ranked passing ANY/A and a just-above-average defensive ANY/A ranked 12th.

Colin has displayed more variance in this stat than any other quarterback in the 2013 season so far. Going from league-leading numbers to cellar-dwelling with Blaine Gabbert is evidence of a couple things to me: (1) at-times frustrating play-calls and (2) The Kid's ridiculous ceiling.

Against a defense selling out for the run -- and specifically the read option -- Kaepernick was able to utilize the aerial attack for an amazing 400-yard performance. But when teams played more traditional and stacked boxes with man coverage on the outside, receivers had a hard time getting open. With the run game not getting its touches, the play-action threat became non-existent. The read option and pistol game died along with it, and Kaepernick and a depleted receiving corps were left to make up for the lack of diversity.

A good amount of Frank Gore and Kendall Hunter in St. Louis last Thursday kept the defense guessing and opened up play-action. The 49ers also began utilizing quick strikes against the Rams, rather than looking for something deep on every snap. This helped Kaepernick get into a groove and it showed in his ball-placement as well as his stat line.

We all hope for much of the same tomorrow. While Kaepernick's 11.32 ANY/A against Green Bay is heavenly, the 7.64 he posted verse St. Louis is more than enough to win games.

Countering Kaepernick's inconsistency is a defense that has handled itself better than the points against statistic indicates.

Outside of the season debut against one of the best quarterbacks in the league, the San Francisco passing defense has held its own. In the past three games, Russell Wilson managed a 4.04 ANY/A, Andrew Luck a 5.63, and Sam Bradord a 3.15.

All three numbers below the respective averages of the signal-caller involved; and for Luck and Bradford it marked their worst performances of the year so far.

Just as we can expect Kaepernick to put up better numbers going forward, we can expect the same from this defense. I do not think the 49ers will stay 17th in ANY/A differential for much longer.