[CTcard]

Well, I have this fun dataset of F+ ranks for the whole PAC going back to 2009, and the defense's best performance relative to the PAC-12 median was actually in 2011 (this says more about the state of the PAC in 2011 than anything else, though). 

The next step is to think about F+ and what does it really measure versus everything else one could use to measure a defense.

F+ does seem to have some strengths, but there are several things that concern me. One is that while they describe the metric in some depth in words, I don't believe they have published enough detail that one could reproduce their numbers on one's own.

More fundamentally, I am suspicious of two things that are done here: one any statistic that is too complicated to simply understand [inherently what does a defensive F+ of 14.3% mean?]; and I also think that a complex, qualitative question like "how good is a defense" cannot be answered by one number regardless of the algorithm. 



There are some things we can certainly say about the recent Stanford defenses.

Against the pass, and versus the competition faced, 2014 was the best overall defensive performance by a lot - this is true in opponents' pass rating, yds/attempt, and yds/game. It's not really close.

Against the run things are more complicated. In both yds/gm and yds/rush Stanford gave up more in 2014 than in 2013, 2012, and 2011 but was a little better than 2010.

In 2014 Stanford was generally less aggressive, blitzing less than recently and also producing fewer turnovers.
Sacks weren't down much, only behind 2012 in sacks/game. I should really check sacks per opponent pass attempt but that is too much work for right now.
Tackles for loss per game are down from 2012 and 2013.
Turnovers gained were 1.25 per game, the second worst since 2008 (better than 2009). This is way behind the 2.3/game from 2010. And a full 1/3 of the turnovers gained in 2014 were from the weenies.

Overall, the actual yds/gm and yds/play were both significantly better this year versus any other over the past seven (which is the timeframe of cfbstats.com).

In scoring, Stanford allowed fewer yds/gm than any recent year (16.0). However, Stanford has been slowing down pace of play. Apparently points per drive allowed was a little behind 2012 and 2010.
http://www.bcftoys.com/2014-ppd
[There aren't links to all years, put the year you want into the URL.]

-----------------
I probably take all of this to mean that 2014 was the best Stanford defense of recent years compared to the opposition they faced. However, I haven't thought much about how good the opposing offenses were in each year - a difficult question to answer with any certainty.

[CTcard]

Well, I have this fun dataset of F+ ranks for the whole PAC going back to 2009, and the defense's best performance relative to the PAC-12 median was actually in 2011 (this says more about the state of the PAC in 2011 than anything else, though). 

The next step is to think about F+ and what does it really measure versus everything else one could use to measure a defense.

F+ does seem to have some strengths, but there are several things that concern me. One is that while they describe the metric in some depth in words, I don't believe they have published enough detail that one could reproduce their numbers on one's own.

More fundamentally, I am suspicious of two things that are done here: one any statistic that is too complicated to simply understand [inherently what does a defensive F+ of 14.3% mean?]; and I also think that a complex, qualitative question like "how good is a defense" cannot be answered by one number regardless of the algorithm. 



There are some things we can certainly say about the recent Stanford defenses.

Against the pass, and versus the competition faced, 2014 was the best overall defensive performance by a lot - this is true in opponents' pass rating, yds/attempt, and yds/game. It's not really close.

Against the run things are more complicated. In both yds/gm and yds/rush Stanford gave up more in 2014 than in 2013, 2012, and 2011 but was a little better than 2010.

In 2014 Stanford was generally less aggressive, blitzing less than recently and also producing fewer turnovers.
Sacks weren't down much, only behind 2012 in sacks/game. I should really check sacks per opponent pass attempt but that is too much work for right now.
Tackles for loss per game are down from 2012 and 2013.
Turnovers gained were 1.25 per game, the second worst since 2008 (better than 2009). This is way behind the 2.3/game from 2010. And a full 1/3 of the turnovers gained in 2014 were from the weenies.

Overall, the actual yds/gm and yds/play were both significantly better this year versus any other over the past seven (which is the timeframe of cfbstats.com).

In scoring, Stanford allowed fewer yds/gm than any recent year (16.0). However, Stanford has been slowing down pace of play. Apparently points per drive allowed was a little behind 2012 and 2010.
http://www.bcftoys.com/2014-ppd
[There aren't links to all years, put the year you want into the URL.]

-----------------
I probably take all of this to mean that 2014 was the best Stanford defense of recent years compared to the opposition they faced. However, I haven't thought much about how good the opposing offenses were in each year - a difficult question to answer with any certainty.