spoiler alert: i linked this
Coaching Change / Offensive Philosophy Change: Time of Possession v. Defense
I originally wasn’t going to post this because I thought it was just a question in my own head, and I didn’t find a signficant result. However, given the top item in Brian’s mailbag today, and since I had already done the quick analysis, I thought it would be worthwhile to share.
The question had to do with whether Michigan’s struggles on defense were related to the fact that its offensive philosophy often results in short possessions, exposing the defense to being on the field for a longer period of time. So I decided to see if there was a correlation between a team’s offensive Time of Possession and its defense.
R-squared is 0.03 - not significant.
“Ok,” I thought, “maybe the way that DFEI is calculated already takes Time of Possession into account. What if we looked at Time of Possession versus Total Defense (yards)? Surely there would be a correlation, especially since defenses that force short possessions by the opponent (3-and-outs, turnovers, etc.) would result in more possessions by their team’s offense, and more Time of Possession.”
R-squared is 0.14 - still not really significant.
“Fine,” I said, “maybe I should look at Time of Possession versus Scoring Defense - because that’s what really counts. An offense that can control the ball can help protect its defense, and keep the score down."
R-squared is 0.06 - not significant.
Finally, I reached back into one of the motivations for looking at this question to begin with. Why would anyone talk about Time of Possession on offense as if it were an important factor on defense, especially with respect to Michigan? Could it be because Stanford leads the country in Time of Possession, and one might try to argue that a CC that shifts the offensive philosophy towards a more ball-control, time-of-possession system would be a good way to help Michigan’s defense?
So what if we looked at the Change in Time of Possession from last year to this year, and compared it to the Change in Total Defense (least insignificant result from above)?
R-squared is 0.14 - still not really significant.
What this says to me is that there are too many variables that influence how a defense performs; one cannot boil it down to a simple thing like Time of Possession (or experience on a depth chart, for that matter). All of those factors may play a part, but no one individual factor is significantly correlated to a team’s performance on defense. Football is just too complex to boil down into simplistic truisms.
***** ADDENDUM *****
A related question has been raised - whether there is a link between the number of possessions and the performance of the defense. I used cfbstats.com to add up the number of 4th down conversion attempts, punts, passing TDs, rushing TDs, FG attempts, Interceptions thrown, and Fumbles lost to calculate the total number of offensive possessions (this may exclude offensive possessions at the end of each half where time simply runs out, and does not differentiate between an offense trying to score v. trying to run out the clock).
Looking at Offensive Possessions versus Defensive FEI:
R-squared is 0.004 - not significant.
What about Offensive Possessions versus Total Defense?
R-squared is 0.13 - still not really significant.
Finally, what about Offensive Possessions versus Scoring Defense?
R-squared is 0.12 - again, still not really significant.
Obviously, if the underlying parameters of a model do not show correlation, one should not expect a calculated value based on those parameters to show a correlation. Nevertheless, for the sake of completion, here is the Average Time per Possession versus Total Defense:
R-squared, as expected, is still only 0.12 - not really significant.
I'm afraid even looking at number of possessions rather than simply time of possession doesn't change the analysis. This suggests to me that the style of offense does not have a significant impact on the performance of the defense.
Last week, there was a thread about an alleged “MGoBubble” (thread ref)- and that led to a side discussion about the perceived level of support for Rich Rodriguez among various groups of people. In my quest to find some real data (rather than forum posts or polls on Detnews), I came across an organization called Public Policy Polling that conducts state-level polls about voter perceptions of political candidates. In May of 2010, they included questions about Rich Rodriguez for their Michigan poll. They repeated those questions in their Michigan poll this past week. The results, both from May and from December, are very interesting and may be surprising to some.
First of all, the usual caveats:
- I am not affiliated in any way with Public Policy Polling (site)
- I am not advocating one way or another anything about “CC” - I am trying to bring some accurate data (and new information) into the discussion
- The survey does not go very deep - it simply asks some basic questions about favorable or unfavorable opinions about RR, and about allowing RR to continue or having him replaced
- The survey does not claim to be representative of any particular subgroup other than the categories it specifically asks about. In other words, this poll is not representative of the UofM student body, nor of alumni. nor of former players, etc. It is representative of registered voters in Michigan who identify themselves as UofM fans, and of those fans as broken down by political ideology, party affiliation, age, ethnicity, and gender.
- The May Michigan survey was conducted May 25-27, polled 890 people, and has a margin of error of +/- 3.3% (source)
- The December Michigan survey was conducted December 3-6, polled 1224 people, and has a margin of error of +/- 2.8% (source)
- One of the questions specifically asks whether the respondent is a fan of UofM, MSU, or neither. The questions about RR were only asked to those who identified themselves as UofM fans. This also means that the margin of error for questions about RR is higher, because the sample size is smaller.
May 2010 Results
First of all, let’s look at the May results, after a 3-9 and 5-7 season, and concurrent with the announcement by Michigan of the self-imposed penalties for the NCAA violations (UofM announced those penalties on May 25).
1. Do you have a favorable or unfavorable opinion of Rich Rodriguez? Based on the May results, it appears that there is a small group of people (20%) who had a favorable view of RR, and a slightly larger but still fairly small group of people (26%) who had an unfavorable view of RR. The majority (54%) were unsure.
The polling organization noted that this is a low favorable rating for one’s own coach. They compared it to the favorable rating that North Carolina fans have for their arch-rival Duke’s basketball coach (46%). For RR to have such a low favorable rating from his own fan base is “exceptionally bad,” according to the polling organization. (source)
2. Would you like to see Rich Rodriguez continue to be Michigan’s football coach this season or would you like to see him replaced? This is a very interesting result - a majority (51%) of people wanted RR to continue for the 2010 season, which implies that a majority of Michigan fans who were “Not sure” of their opinion on RR still wanted him to be the coach. In fact, there was a smaller percentage of fans who wanted him replaced (20%) than who had an unfavorable opinion of him (26%), which implies that even some of his detractors either wanted him to continue as coach this year or were unsure.
Digging a little bit deeper, although this poll doesn’t say anything specifically about UofM students, alumni, current players, or former players, it is possible to address whether age has anything to do with one’s positions on RR. A claim that I have heard on this blog is that RR’s detractors are probably older fans who are more comfortable with traditional power football, and not inclined to support a coach who brings a modern offensive philosophy to the table. In fact, this data appears to show just the opposite - the older the fan, the stronger the support for RR in May. It is the group of fans in the youngest category (18-29) who are the most polarized and who have the strongest negative views on RR.
Why is that? One possible explanation is that the idea of keeping something the same or making a change may be related to one’s political ideology - and that as of May 2010, having RR as the coach was already seen as the status quo. Assuming (the polling organization didn’t publish this specific data) that older fans tend to be conservative, and further assuming that conservatives prefer to keep the status quo, that might partially explain why older fans preferred to keep RR as coach back in May. In that sense, one could argue (although the data doesn’t necessarily say this) that RR was already accepted by those older fans as “a Michigan man” in the sense that his status as football coach was seen as the status quo.
One final interesting result from the May survey. There does appear to be a significant divide in support for RR based on ethnicity. The polling organization didn’t put forward any possible explanation for this ethnicity gap, and I honestly can’t come up with a rationale myself. It is what it is.
A lot has happened in Michigan since May, both in football and in politics. Michigan elected a Republican governor by a large majority, and the UofM football team experienced a winning season under Coach Rodriguez, but suffered double-digit losses to MSU, Iowa, Wisconsin, and OSU.
So how did the events of the past 6 months affect RR’s favorable rating among UofM fans?
There remains a small core of people (20%, just as in May) who continue to have a favorable opinion of RR, while the group that has an unfavorable opinion has increased (from 26% in May to 38% in December), apparently almost completely from the “Not sure” camp in May (down from 54% in May to 42% in December). The surprising result, for me, is that the largest group (42%) is still “Not sure” about their opinion of RR.
Given that many “Not sure” fans in May still wanted RR to continue, and even some of the fans who viewed RR unfavorably in May didn't necessarily want him replaced, do fans want RR to continue as they look forward to 2011?
Again, there has been a shift in opinion away from a majority of people who wanted RR to continue back in May, to a statistically even split among those who want him to continue (32%), those who want him replaced (35%), and those who are unsure (33%). As in May, there may be some people who have an unfavorable view of RR but do not necessarily want him replaced (38% v. 35%).
Attempting to tease out where those unsure of their opinion of RR stand with respect to having him keep his job, I made a couple of admittedly invalid assumptions:
- All those who want RR to continue have a favorable opinion of him
- The difference between the larger group of those who want RR to continue v. the smaller group of those who have a favorable opinion of him consist completely of those who are unsure of their opinion of him. In other words, if 20% have a favorable opinion, but 32% want him to continue being the coach, that extra 12% of people who want to keep RR is coming from those who are unsure of their opinion of him.
Not sure of their opinion of RR but want him to continue
Again, this is probably a stretch in terms of interpreting the published data, but it appears that RR’s support for keeping his job among “neutral” UofM fans has eroded significantly.
Digging a little deeper, the May results suggested that the youngest fans (18-29) were the most strongly divided and had the highest percentage of people wanting to replace RR. By contrast, the oldest fans (65+) wanted to keep RR back in May, by a large margin. Has this age profile of support for RR changed in December?
This is a significant change. Not only has RR’s overall support eroded, his support among the “blue hairs” has completely flipped, where more of the oldest respondents (65+) want him replaced than want to keep him.
Respondents age 65+
What about the youngest respondents, who were the most divided back in May? It appears that they are now very unsure of whether they want RR to continue being Michigan's coach.
Respondents age 18-29
What about political ideology? Do even conservative fans, who theoretically would prefer to keep the status quo, still want to keep RR in his position?
Again, this shows almost a complete inversion of the results in May. Back in May, liberals tended to want to replace RR while conservatives tended to want to keep him; now in December, it’s the opposite.
And for the sake of completion, do we still see a dramatic gap in support for RR based on ethnicity?
Although there is still an ethnicity gap, it has narrowed significantly to the point where it appears that one either wants RR to continue, to be replaced, or is unsure - regardless of one’s ethnicity.
Finally, one additional question was asked in the December poll, about who the respondents would like to see as a replacement. No surprise about who leads the pack, but I should point out that Brady Hoke is running a distant third, behind even an “unnamed” candidate.
I’ll be the first to say that it is dangerous, even maliciously deceptive, to extrapolate into the future using data that is not intended to be used that way. So I believe it would be inappropriate to say anything like, “if current trends continue...”, or “another season like this one would probably result in favorable ratings of...”, or “if we lose to MSU and OSU again next year, the percentage of fans who would want to keep RR would probably be...” The data makes no claim to predict the future - it is simply 2 snapshots in time that reveal how opinions have changed since May.
I hope this diary qualifies as “bringing new information” to the table, and also brings forward some reasonably accurate opinion survey data that we can talk about, rather than statements made in a vacuum claiming that “98% of former M football players still alive despise RR” or the idea that “players that played 40-70 years ago...are not a fan of the spread offense...” (thread ref)