Defensive TOP per Drive

Submitted by jokewood on October 8th, 2009 at 2:59 PM

After reading other people's thoughts about last week's performance, I am confused by the willingness of some to give the defense a passing grade because they held Michigan State to "only" 20 points. Overall, I agree that the offense did a worse job than the defense, especially considering they are the stronger of the two units. That said, this was most definitely a team loss. I don't find compelling the argument that "if you would have told me before the game that we would hold MSU to 20 points, I would be ecstatic."

When I evaluate defensive performance, I look at how well the defense has accomplished two "universal" objectives. While some coaches may make field position or turnovers a high priority, I think the majority would find these two objectives critical...

1. Minimize Points Scored per Drive Except in rare end-of-game situations, you never want your defense to allow the opponent to score. The total points given up by the defense is a factor of how often the defense sees the field (total # defensive "drives") and how well the defense performs each time it sees the field (def pts allowed per drive). Other factors like field position and offensive performance (protecting the defense) contribute as well. Of these, the defense has the greatest control over the defensive points allowed per drive - DEF PPD. In my view, a defense that gives up 24 points in 12 possessions has performed better than a defense that gives up 24 points in only 8 possessions.  
But what I really want to talk about today is goal #2... 2. Minimize Defensive Time of Possession (TOP) per Drive Quite simply, get the ball back to your offense so they can score.  No coach wants the other team to hold onto the ball. RR has stated this is one of the key objectives of his defenses. Also, defense, heal thyself - get off the field. The defense has equal share in winning the overall TOP as the offense. You can't reasonably expect the offense to win the game if the defense is not giving them sufficient chances to succeed.
Metric: Defensive TOP Per Drive (DEF TOP/D). This measures the average time the defense leaves the opposing offense on the field per possession. Here is how defensive TOP/drive correlates to outcomes over the years 2001-2007, 2009. I excluded the 2008 season because no useful data can be extracted from that historically bad team other than "we sucked."
Avg. DEF TOP/drive >2.5 min... 11-15 (0.423) Avg. DEF TOP/drive 2.4-2.5 min... 11-5 (0.689) Avg. DEF TOP/drive <2.4 min... 46-5 (0.902) In Saturday's loss, the defense left MSU's offense on the field for 3.6 minutes per possession in regulation. This defensive TOP/drive was the highest I found in my research going back through 2001 (even in the excluded 2008). No other game was close. In the first half, the defense averaged over 5.5 minutes per drive. Even if they held MSU to only 10 points in that half, saying they did a decent job is only telling half of the story.

Here is the raw data:
DEF TOP/D (min) -- Games (losses in bold italics) 3.6 - 09 MSU (L) 3.2 - 05 OSU (L), 02 Iowa (L) 3.1 - 09 EMU, 02 OSU (L) 3.0 - 03 CMU 2.9 - 07 Wisc (L), 05 Wisc (L), 04 Ind, 03 Ore (L) 2.8 - 06 MSU, 05 NIU, 05 PSU, 02 PSU 2.7 - 06 USC (L), 05 Minn (L), 04 NW, 04 Tex (L), 01 Wash (L) 2.6 - 09 ND, 06 Ind, 06 OSU (L), 04 OSU (L), 03 USC (L), 01 WMU, 01 MSU (L) -------------------------- 2.5 - 07 OSU (L), 06 NW, 05 MSU, 03 Ind, 02 Wisc 2.4 - 07 Ore (L), 07 EMU, 07 Minn, 06 MSU, 05 ND (L), 03 Minn, 02 ND (L), 02 Wash, 02 Pur, 01 Wisc, 01 Tenn (L) -------------------------- 2.3 - 07 PSU, 07 NW, 07 Ill, 07 Fla, 06 Iowa, 04 MSU 2.2 - 07 AppSt (L), 07 ND, 07 MSU, 06 Minn, 06 Vandy, 05 Iowa, 03 NW 2.1 - 09 WMU, 06 BSU, 03 Ill, 03 OSU, 02 WMU, 01 MU 2.0 - 09 Ind, 07 Pur, 05 EMU, 04 MU, 04 Iowa, 04 Ill, 02 Ill, 02 MSU, 02 Minn, 01 Pur, 01 Minn, 01 OSU (L) 1.9 - 06 ND, 06 Wisc, 04 SDSU, 03 ND, 03 MSU, 03 Iowa (L), 01 PSU, 01 Iowa 1.8 - 06 CMU, 05 Ind, 05 Neb (L), 03 Hou, 03 Pur 1.7 - 04 ND (L), 02 Utah, 02 Fla 1.6 - 04 Minn, 04 Pur, 01 Ill 1.4 - 05 NW  


Enjoy Life

October 8th, 2009 at 4:12 PM ^

TOP is often a reflection of the type of offense a team uses. Teams that run the ball tend to have significantly higher TOPs than passing teams -- even though they have the same Number of Plays.

You do realize that the difference between 2.3 and 2.4 is a mere 4.3%? Are you suggesting that a 4% difference is meaningful?

Also, how does a team end up with TOP of 1.4, 1.6, etc.? If you line up and run the ball three times and punt, it should be around 2.0.

Miss Meeechigan

October 8th, 2009 at 5:13 PM ^

How can you not give credit for holding the MSU offense when they were inside the 10? I will admit that watching MSU's 10+ minute driving was one of the most painful things that I've ever had to watch. I'm sure that our D didn't really enjoy it either.


October 8th, 2009 at 5:46 PM ^

I'd be curious to see the #'s adjusted for points per play. Heck, even compare MSU's previous games on a points per play basis. I'd bet we gave up fewer points per play (or plays per point if you want a >1 metric) than the average. I'd surmise that, in the end, if you can minimize the number of expected points per play you will most certainly have a greater chance of winning.

So - do you have those numbers?


October 8th, 2009 at 8:14 PM ^

I think the next metric would be "defensive number of plays per possession". The next one after that is "defensive number of first downs per possession". The one after that is "defensive number of points per possession".

I guarantee you we are more likely to win games if we keep these numbers down. No joke!


October 8th, 2009 at 9:48 PM ^

"In my view, a defense that gives up 24 points in 12 possessions has performed better than a defense that gives up 24 points in only 8 possessions."