How do you judge a good defense?

[wiskibreth]

don't complicate things;  points allowed.

[Bob in STL]

3 hours ago, Over 29 years of fanhood said:

Points.  Rex proved that you could win some other metrics and still field a loser. 
 

the defense has one job, prevent Opposition scoring 

You look at everything, every detail counts. 
 

The Bills lost Super Bowl by 20-19.  Giving up 20 points was ok.   Giving up yards, first downs, time, and failing to get off the field on 3rd was a problem.  
 

Lots of ways to measure effectiveness.  
 

 

Edited April 15, 2020 by Bob in STL

[SoCal Deek]

The best statistic, and I don’t know if they actually keep it, would be yards allowed per drive/possession. It would take almost everything else into account. 

[Ridgewaycynic2013]

Joe Brown.  Judy Sheindlin is too opinionated.

[Over 29 years of fanhood]

26 minutes ago, Bob in STL said:

You look at everything, every detail counts. 
 

The Bills lost Super Bowl by 20-19.  Giving up 20 points was ok.   Giving up yards, first downs, time, and failing to get off the field on 3rd was a problem.  
 

Lots of ways to measure effectiveness.  
 

 

It wasn’t ok for me. They lost because the giants defense only allowed 19 points and the bills defense allowed 20. 
 

measuring anything other than points is for moral victories imo. 

[Mr. WEO]

46 minutes ago, Thurman#1 said:

Picking one?

 

Yards Allowed.

 

Points Allowed is more important, but it isolates the defense very poorly. For example, if your QB throws a pick six, Points Allowed puts the blame for that on your defense, which is outright dunder-headed. If your RB fumbles and the other team recovers on your 1 yard-line and takes four plays to hammer it in, again, Points Allowed blames your defense seven points worth for what was actually a pretty decent defensive series. Worse, if on the same fumble, your defense sacks them three times, forcing a 42-yard field goal, Points Allowed blames your defense for what is actually a resounding success.

 

Defense holds the opposing offense to zero yards on three plays? Your returner fair catches? Your offense gains zero yards on three plays and the opponent runs the punt back for a TD? Points Allowed says your defense is at fault.

 

The defense is probably somewhere in the neighborhood of 60% - 75% responsible for Points Allowed. Field position is huge in how likely a team is to score on any give drive, and the offense and STs have tremendous say in how bad or how good the opposing offense's field position is. Number of drives faced is also huge in how successful your defense will be in Points Allowed. If your defense faced 20 more drives than another team did, they'll allow more points even if they're exactly as good. And again, offense has a huge role in how many drives your defense will face.

 

Yards Allowed almost completely isolates the defense. Over the course of a season yards defended will not be wildly different from team to team.

 

Is it a perfect measure? Nah, far from it, there is none that's close. Turnovers in particular are also big, though some of that - particularly fumbles caused vs. fumbles recovered - comes down to luck. But if you have to pick one, Yards Allowed is probably the best. That's why it's how defenses are ranked.

 

 

Turnovers that quickly lead to TDs are rare.  So are returns for TDs.  There's no way they come close to accounting  for 25-40% of opponent points scored.

 

The Vikings D gave up a ton of yards (19th in the league), but only 18.9 ppg (5th).  Ditto for the Chiefs: tons of yards, but only 19 ppg (7th---and many here rag on that D as awful).  Both teams only gave up 3 more than the Bills.

 

So it's PPG

[Don Otreply]

Points allowed mostly, that and win loss, yards, passing,  and run stats fill in the grey areas. It all comes down to scoring and stopping the other guy from scoring. 

[hondo in seattle]

Most of us will look at points per game and yards per game.  But as the "eye test" tells, those stats don't tell the whole story.  If the offense is giving up lots of 3-and-outs, losing the battle for field position, and coughing up the ball, that team's defense will suffer the consequences.  

 

One of my favorite stats is yards per drive.  It's not perfect either but a good D will not give up a lot of yards per drive.   Defenses that face a lot of drives because of their inept offense will not be disadvantaged in the yards-per-drive statistical rankings.  

Edited April 15, 2020 by hondo in seattle

[Orlando Tim]

It truly must be the eye test since it is such a short season that two games where team  A plays an awful offense and team B plays great offenses can easily skew the numbers of what are otherwise equal teams.

[C.Biscuit97]

5 hours ago, GunnerBill said:

Points, yards, turnovers in that order  

Yeah and as others have pointed out 3rd down conversion %.  I also think there are other factors that should be considered.  Field position is huge.  One of the reason people think TB can be really good is because their defense played better than normal stats would show because Winston put them in a lot of bad situations with turnovers.  So a crappy offense can really hurt a defense. 

[Dr. K]

Points allowed, though that may not reflect the defense's play completely accurately. But it's what counts in the end. 

[Johnnycage46]

6 hours ago, BritBill said:

When you're assessing if a team has a good/great/elite defense what yardstick do you use?

 

Yards allowed? Points allowed? Third down stops? 3 and outs? Sacks?

 

Let me know your thoughts? 

Points allowed and 3rd down efficiency I think are pretty good indicators.

[C.Biscuit97]

32 minutes ago, hondo in seattle said:

Most of us will look at points per game and yards per game.  But as the "eye test" tells, those stats don't tell the whole story.  If the offense is giving up lots of 3-and-outs, losing the battle for field position, and coughing up the ball, that team's defense will suffer the consequences.  

 

One of my favorite stats is yards per drive.  It's not perfect either but a good D will not give up a lot of yards per drive.   Defenses that face a lot of drives because of their inept offense will not be disadvantaged in the yards-per-drive statistical rankings.  

Good post.  This is one of those things where more analytics is very helpful.  https://www.footballoutsiders.com/stats/nfl/overall-drive-stats/2019
 

as I mentioned with TB, in terms of scoring defense, they gave up 28 points a game, 4th worst in the nfl.  But they were 8th best in yards per drive.  Jameis killed them.  

[Bob in STL]

8 hours ago, Over 29 years of fanhood said:

It wasn’t ok for me. They lost because the giants defense only allowed 19 points and the bills defense allowed 20. 
 

measuring anything other than points is for moral victories imo. 

We are talking about measuring a good defense.   Points allowed is one very good measure, but not the only one.  Certainly the ability to shut down the other team, not give up long time consuming drives, and get the ball back is important as well.  

[GoBills808]

Yards

 

Don't overthink it

[Over 29 years of fanhood]

3 minutes ago, Bob in STL said:

We are talking about measuring a good defense.   Points allowed is one very good measure, but not the only one.  Certainly the ability to shut down the other team, not give up long time consuming drives, and get the ball back is important as well.  

I get you and sure but the outcome of turnovers, big stops, and not allow long drives are preventing points.

 

my take is I care nothing about how a defense keeps you out of the end zone as long as you do. 

[LABILLBACKER]

12 hours ago, BritBill said:

 

I'm unsure. I've kind have been a points allowed chap but that can be skewed slightly like yards allowed by garbage time vanilla defense but maybe not as much. 

 

What about red zone points against? 

 

Also does everyone apply the same rules to judging an offense as they do a defense?

 

 

Too bad there isn't some formula that combines points allowed and yardage allowed like a qbr?

[Mikie2times]

I like yards per play and points. But even then, both stats have shortcomings. You need to really look at several stats as a whole 

 

Edited April 15, 2020 by KzooMike

[Cruiserplayer]

Drives that are nine plays or less that the offense doesn’t score unless they have less than 20 yards to get in scoring range. Good luck finding that so eye test.

[Happy]

Points allowed followed by yards allowed.  If those are low (good for the defense) then that means you've done everything else in support of those metrics right.