Introduction

Hello,

We are halfway through the 2023 NFL season, and I wanted to do a quick look into some metrics pertaining to the QB position.

The two main ones are Completed Air Yards (“CAY”) and Success Rate (“Succ%”)

Completed Air Yards are the amount of yards traveled past the line of scrimmage minus Yards After Catch. Success Rate measures if a play gains at least 40% of yards required on 1st down, 60% of yards required on 2nd down, and 100% on 3rd or 4th down.

I decided to look at CAY because it controls for Yards After Catch, and may be more indicative of a QB’s passing abilities. For instance, if a QB throws a slant for 5 yards, but it goes for a 50 yard TD, that was less a consequence of the QB and more a consequence of the receiver and blocking by teammates. Granted, football is a team sport, and even just looking at that is not a comprehensive look at the greatness of a QB; however, that coupled with Succ% gives some insight I think.

Again, not comprehensive, and that is not really what I am trying to go for anyway, but this is more so just to share some interesting findings.

Methodology

All data was taken from Pro Football Reference. I only chose QBs with a minimum of 97 pass attempts. The different metrics I looked at include CAY, CAY/PA, CAY/Cmp, and Succ%.

After copying all the data, I found the Z-score for each individual and their corresponding metric. Then, I did a two-tail test to see which Z-scores were statistically significant. I set alpha to 0.05.

Findings

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Table 1

The table above is the dataset pertaining to each individual QB with their corresponding metrics.

Table 2

This table shows the Z-scores for each individual QB and their corresponding metric. The areas highlighted in green are Z-scores that were determined to be statistically significant.

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Table 3

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Table 4

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Table 5

Tables 3-5 just show the graph version of the datasets from tables 1 and 2.

Z-Score Discussion

The only areas that were found to be statistically significant were the following:

P.J. Walker - CAY (lower end of distribution)

P.J. Walker - CAY/PA (lower end of distribution)

Joe Burrow - CAY/Cmp (lower end of distribution)

Brock Purdy - CAY/PA (upper end of distribution)

Brock Purdy - Succ% (upper end of distribution)

Matthew Stafford - CAY/Cmp (upper end of distribution)

The higher the success rate, obviously the better, and with Purdy his success rate is statistically significant. Some QB’s that are close to the upper end (but for whom we would not reject the null hypothesis for) in terms of success rate only really include Allen, Tua, and Goff. On the lower end, Watson, Walker, Wilson and Jones are close, but again, do not cross that critical value of -1.959964.

Limitations

This is not all-encompassing. As far as assessing the QBs, Completed Air Yards and success rate are only part of the equation. There are non-football stat related things to keep in mind, such as personality, experience, age, teammates, and coaches. Taking those into account can help explain why the data is the way it is.

Additionally, a QB can make a great play not through the air. They could very well rush for a big gain or even a TD. This analysis only views the QB position through the prism of passing.

Conclusion

Overall, I think this is interesting, but incomplete. Further inquiry can be made to give a more comprehensive view of the QB position. However, with the metrics we are examining here, I think it is a decent start. Another analysis of this, with more metrics and at the end of the season, would probably be more insightful.

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  • splat_edc@alien.topBEnglish
    1·
    10 months ago

    First off, thanks for putting this together. Interesting stuff to dig into.

    For the two-tailed z-scores does that mean looking for scores greater than/less than +/- 1.96 or am I thinking of something else?

    On the success rate numbers, are those only for pass attempts or do they include things like QB scrambles? I noticed that Mahomes has a decent success rate but is below average in these passing metrics. Could that be due to his ability to pick up yards/first downs with his legs? I’m assuming success rate doesn’t distinguish between air yards and YAC, so for somebody like Mahomes (Ridder has the opposite thing going with bad success but decent CAY) can we attribute the success to YAC or is that an unjustified leap?

    • PsychologicalGuest97@alien.topOPBEnglish
      1·
      10 months ago

      1.) If alpha is set to 0.05, for two-tail, you find the upper and lower critical values (all you need is to find one and use symmetry to find the other). So after doing the math, the closest value on the Z chart is 1.959964. Anything between -1.959964 and +1.959964 is not statistically significant, so we therefore fail to reject the null hypothesis.

      2.) Success Rate is only looking at passing. There is a separate Succ% for rushing

      3.) I think Mahommes is having a down year based off his previous seasons. Could be due to Kelce injury, strength of opponent, and that flu game. May not explain all of it, but maybe some.

      4.) Not sure I understand your last question. A 6 yard gain on 3rd and 10 would not be a successful play, and if it were accomplished with his legs it would not count toward the Succ% above