Football 101: QB Rating System

[Hostile]

We've all seen the QB ratings to gauge how well a guy has done. It is a complicated system of calculations. I thought I'd take a minute to explain them. Hope it doesn't hurt anyone's head.

First of all there are 4 initial calculations that you need. For the sake of this discussion I am going to call them A, B, C, & D. I am going to put in bold the stats you need in order to calculate the QB rating. Note that # of attempts is used in each Calculation.

No calculation will exceed 2.375. No calculation will be lower than zero. So if you get a number greater than 2.375 once a calculation is done, the number you plug in will actually be 2.375. If you get a number lower than 0 the number will be zero.

A. The calculation for completion %.

1. # completions is divided by # of attempts.
2. This number is then multiplied by 100.
3. Take that number and subtract 30.
4. Divide that number by 20.

This is the number you will plug into the formula later for the Letter A.


B. The calculation for yards per attempt.

1. # of yards is divided by # of attempts.
2. Take that number and subtract 3.
3. The new number is multiplied by .25.

This is the number you will plug into the formula for the Letter B.


C. The calculation for Touchdowns per attempt.

1. # of TD passes is divided by the # of attempts.
2. This number is multiplied by 20.

This is the number you will plug into the formula for Letter C.


D. The calculation for Interceptions per attempt.

1. # of Interceptions is divided by # of attempts.
2. This number is multiplied by 25.
3. The new number is subtracted from 2.375. (Note: do not subtract 2.375 from the number in line 2. Subtract the number in line 2 from 2.375.)

This is the number you will plug into the formula for Letter D.


Now you will use these 4 calculations and make one final number which is the QB rating.

1. Add A + B + C + D.
2. Divide this number by 6.
3. Multiply the new number by 100.

This gives you the QB rating.

This can be done for 1 game, a group of games, an entire season, or a career. You just need to know those stats to calculate the QB rating.


As an example, here is how Tony Romo's QB rating for Sunday is calculated.

# Completions = 16
# of attempts = 27
# of yards = 353
# of TDs = 3
# of INTs = 0

A = (16 / 27 * 100 - 30) / 20
A = 1.463

B = (353 / 27 - 3) * .25
B = 2.519

C = 3 / 27 * 20
C = 2.222

D = 2.375 - (0 / 27 * 25)
D = 2.375

(1.463 + 2.375 + 2.222 +2.375) / 6 * 100 = 140.583


Tony Romo's QB rating for Sunday was 140.583. Different stats services will round it off differently. I carried it out to 3 decimal places because the D calculation already has 3.


Now, if you will excuse me, my head hurts.

 

[Four]

when I signed up for this site I was under impression there would be no math

you sir have shattered a dream

 

[ABQCOWBOY]

Nice explination Hos. I'm not surprised you head hurts. Mine does to.

:laugh2:

 

[cowboyfan4life_mark]

wat djew sia? :grin2:

 

[GimmeTheBall!]

Dang, Hos, that was impressive. Seriously.

I always wanted to be smart but I will take charming most days.

 

[kmd24]

That's not totally correct, Hos. You must cap each term at 2.375, so the second term in the calculation for Romo's rating should be 2.375 instead of 2.519, and that's why his official NFL rating is 140 instead of 142.

It's also why Brees's rating is 137 instead of in the 150's. His TD term would be 3.53.

 

[Hostile]

when I signed up for this site I was under impression there would be no math

you sir have shattered a dream

Again?

Aw hell man. I sowwy. Fohgive me?

 

[casmith07]

Hos --

I've got the whole mathematical stuff down, but my question is do you know if there's any basis to why certain numbers/variables are used in the calculation? Why did they pick .25, for example, or this equation at all instead of something more simple?

 

[Nav22]

NFL.com has Tony's rating at 140.6, as does http://www.primecomputing.com/ when you manually enter in his stats.

 

[Hostile]

That's not totally correct, Hos. You must cap each term at 2.375, so the second term in the calculation for Romo's rating should be 2.375 instead of 2.519, and that's why his official NFL rating is 140 instead of 142.

It's also why Brees's rating is 137 instead of in the 150's. His TD term would be 3.53.

Thank you. I forgot that.

 

[Four]

Again?

Aw hell man. I sowwy. Fohgive me?

you can save that kinda talk for WG, she is into it.

 

[Plumfool]

If there's a test later I'm using my notes.

 

[Hostile]

NFL.com has Tony's rating at 140.6, as does http://www.primecomputing.com/ when you manually enter in his stats.

Yeah, I forgot one thing as I was typing the formula down. That number above is correct.

I have fixed mine.

 

[SLATEmosphere]

Those arbitrary "subtract 100 then divide by 20" definitions are a bit silly. It's totally unnecessary.

And I love how a QB goes 31-35 for 400 yards and 3TD's and it's a perfect QB rating. He missed 4 passes. Obviously not "perfect"

Thanks for sharing though.

 

[CF74]

 

[Hostile]

Hos --

I've got the whole mathematical stuff down, but my question is do you know if there's any basis to why certain numbers/variables are used in the calculation? Why did they pick .25, for example, or this equation at all instead of something more simple?

I remember reading those one time, but I don't remember what the answer was. Had something to do with Historical averages and a range between them.

I honestly cannot explain that part at all.

 

[Hostile]

If there's a test later I'm using my notes.

It is a 1 question test.

Best team ever?

I think you'll do fine.

 

[Clove]

We've all seen the QB ratings to gauge how well a guy has done. It is a complicated system of calculations. I thought I'd take a minute to explain them. Hope it doesn't hurt anyone's head.

First of all there are 4 initial calculations that you need. For the sake of this discussion I am going to call them A, B, C, & D. I am going to put in bold the stats you need in order to calculate the QB rating. Note that # of attempts is used in each Calculation.

No calculation will exceed 2.375. No calculation will be lower than zero. So if you get a number greater than 2.375 once a calculation is done, the number you plug in will actually be 2.375. If you get a number lower than 0 the number will be zero.

A. The calculation for completion %.

1. # completions is divided by # of attempts.
2. This number is then multiplied by 100.
3. Take that number and subtract 30.
4. Divide that number by 20.

This is the number you will plug into the formula later for the Letter A.


B. The calculation for yards per attempt.

1. # of yards is divided by # of attempts.
2. Take that number and subtract 3.
3. The new number is multiplied by .25.

This is the number you will plug into the formula for the Letter B.


C. The calculation for Touchdowns per attempt.

1. # of TD passes is divided by the # of attempts.
2. This number is multiplied by 20.

This is the number you will plug into the formula for Letter C.


D. The calculation for Interceptions per attempt.

1. # of Interceptions is divided by # of attempts.
2. This number is multiplied by 25.
3. The new number is subtracted from 2.375. (Note: do not subtract 2.375 from the number in line 2. Subtract the number in line 2 from 2.375.)

This is the number you will plug into the formula for Letter D.


Now you will use these 4 calculations and make one final number which is the QB rating.

1. Add A + B + C + D.
2. Divide this number by 6.
3. Multiply the new number by 100.

This gives you the QB rating.

This can be done for 1 game, a group of games, an entire season, or a career. You just need to know those stats to calculate the QB rating.


As an example, here is how Tony Romo's QB rating for Sunday is calculated.

# Completions = 16
# of attempts = 27
# of yards = 353
# of TDs = 3
# of INTs = 0

A = (16 / 27 * 100 - 30) / 20
A = 1.463

B = (353 / 27 - 3) * .25
B = 2.519

C = 3 / 27 * 20
C = 2.222

D = 2.375 - (0 / 27 * 25)
D = 2.375

(1.463 + 2.375 + 2.222 +2.375) / 6 * 100 = 140.583


Tony Romo's QB rating for Sunday was 140.583. Different stats services will round it off differently. I carried it out to 3 decimal places because the D calculation already has 3.


Now, if you will excuse me, my head hurts.

In other words, he played good.

 

[Hostile]

In other words, he played good.

I was told all off season by you that this was impossible.

 

[Clove]

I was told all off season by you that this was impossible.

I also said he would have good games but magically you forgot that. I think we have 15 more games to go.