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A Statistical Look At Colin Kaepernick

USA TODAY Sports - Kyle Terada

It seems like no one wants to sign Colin Kaepernick this offseason. Everything subjective aside, how was his statistical performance last season?

Regardless of your opinion of him or the surrounding issues, the Colin Kaepernick narrative has remained a part of the NFL since last season. The biggest question now is, will he ever play for an NFL team again?

While many argue that separating the player from the play is near impossible, for the sake of this article, let’s analyze just the statistical side of Colin Kaepernick’s performance last season. This is by no means an effort to take an evaluative position on Kaepernick, but rather is simply a presentation of a perspective purely based on statistics.

The Basics

Last season, Colin Kaepernick played in 12 games and started 11 of them for the San Francisco 49ers.

His 59.2% completion rate ranked above just four other quarterbacks with at least 300 attempts last year: Brock Osweiler, Blake Bortles, Ryan Fitzpatrick, and Cam Newton (fantastic company to be in). Of qualifying quarterbacks, Kaepernick finished dead last with fewer than 190 yards per game last year, which goes along with his second to last 5.54 net yards per attempt.

Certainly in most categories, Kaepernick was at or near the bottom in passing stats last season. 

However, in those games, Kaep threw 16 touchdowns to just four interceptions. While his bottom feeding partners like Osweiler, Keenum, and Fitzpatrick all sit at the bottom in terms of touchdowns to interceptions, it is striking that Kaepernick actually tied for sixth in the league last season with a 4.0 TD to interception ratio. This put him up with the likes of Derek Carr, Sam Bradford, and Marcus Mariota; clearly much better company than the other signal callers mentioned above.


Related to his surprisingly competent ratio, Kaepernick’s touchdown and interception rates also ranked favorably in the league. Kaep finished just above the middle of the pack in touchdown rate and an impressive sixth for interception rate. To be fair, his touchdown rate could be related to the garbage time games he played in, inflating those stats a bit, but the interception rate certainly speaks to, at least, a respectable level of decision making from the 29-year-old.

Only because you can’t talk about Kaepernick’s play without including his rushing, we’ll take a quick look here. Last year, Colin put in 69 rush attempts (about six per start) for 468 yards and two touchdowns. While this looks pretty decent, let’s also mention the nine fumbles he had—that’s a 13% fumble rate. While the interception total looks good, these nine fumbles paint a picture of a turnover-prone quarterback.

A Deeper Look

Passer Rating

In his 11 starts, Kaepernick could only put together one win; a one-point victory against the L.A. Rams who were as good as a team without a proper NFL coaching staff. That said, Kaepernick actually was above average in passer rating in the majority of his games. When averaged out, the average passer rating for signal-callers with 300+ attempts last season came out to 91. To compare, Kaep posted six games, out of the 11 total, with a rating higher than 91, despite his average for the season falling four points below this marker. 

This could be interpreted in different ways.

One, it could mean that Kaepernick’s performances were highly inconsistent last season, causing his average to be lower than the rest of the league but with more above average games. Two, it could indicate that Kaepernick was above average more often than not, but a couple of really poor performances dropped his average severely. 


Removing Kaepernick’s five-attempt game against the Chicago Bears actually brings his average passer rating up to 92.2, a score we are more likely to expect given his number of above average games. An outlier is certainly to blame for this discrepancy.

So, it seems as though, in terms of rating, Kaep was actually above average in the NFL last season, but we need to remember that garbage time was a factor in many Niners games last year. 

To give this idea some quantification, we can look to Football Outsiders’ rating of quarterbacks last season, as they take account of the game situations in which these players throw. This gives us a more accurate view of Kaep’s production last season, and the rankings have the San Fran QB at 30th, right above, yup, you guessed it: Keenum, Fitzy, and Osweiler. If anything, this tells us that passer rating deserves little to no respect in comparing players.

Also, here, we can look to Football Outsiders’ rating of Kaepernick’s running last season. Although he had the most most rush yards among quarterbacks when adjusted (DYAR), his effectiveness per play (DVOA) ranked fourth in the league. This ranked below players like Kevin Hogan (an outlier), Dak Prescott, and Brock Osweiler. So, certainly, while Kaep’s running added some value to the Niners, it was nothing special relative to the rest of the league or even historically.

Impact on Team Performance

While doing this with straight statistics is nowhere near perfect or even that great, we can try to find loose relationship comparisons with Kaep’s stats from last year. Given our situation, I took point differential as a quantification of team overall performance and game result and ran regressions against it. For instance, below we can see point differential (PD) regressed against Colin Kaepernick’s respective passer ratings. Although passer rating is not an all-encompassing stat, it does decently in terms of comparing pass production between games for a single player.

PD x Passer Rating Graph

With a coefficient of correlation (the correlation factor) of .246, Kaepernick’s passer rating came out to be loosely positively correlated with the point differential of games he started in last season, barring the outlier mentioned previously. 

In comparison, below we have point differential regressed with Kaepernick’s rushing yards. I ran this regression in hopes to find some relationship between Kaep’s rushing production and the outcomes of Niners games.

PD x Rush Yards Graph

Although there was not much correlation between the two variables, you can see that there was a tiny negative correlation between point differential and rush yards. In this case, it tentatively seems as though Kaepernick’s rushing is not a great indicator (or indicator at all) of his team’s success. Overall, it seems that Kaep’s passing production has more to do with the team’s performance than his rushing.

If this is the case, we can also take a closer look at his passing. Here, I took a regression of point differential and completion percentage. A coefficient of correlation of .649 and p-value under .05 was enough to let me know that I found a good relationship.

Image title

To compare, I also took PD and looked for a correlation with Kaepernick’s adjusted yards per attempt in his games. The resulting graph looked like the following:

Image title

Although the coefficient came out to be over .95, the .6+ p-value and and R-square of .03 indicated that there was little I could take from this correlation. Apparently, completion percentage of Kaepernick was a much better indicator of the Niners’ performances last season than his adjusted yards per attempt.

The numbers are laid out here for you to evaluate if that’s what you want to do. Coaches and front offices around the league likely have far more than what’s written out here to look at and evaluate Colin Kaepernick with. Putting everything else aside, given his performance last season and the numbers presented here, would you give Kaepernick a chance? 


Edited by Emily Berman, Coleman Gray.

SQuiz
What pick did the San Francisco 49ers draft Colin Kaepernick?
Created 6/7/17
  1. 7th overall
  2. 14th overall
  3. 36th overall
  4. 119th overall

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