Rating Strength of Schedules and Comparing those of the top Contenders

Catch 5's picture
November 21, 2013 at 2:37 pm

A few days ago, user Alex Pavlick wrote an entry in the forums about OSU's current win streak and the probability of it occurring.  He used Vegas odds to determine the likelihood of individual wins and used that to calculate the probability of winning them all.  It is an entirely valid exercise but I disagree with using Vegas odds for the data set.  Vegas odds are figured from the perception of those teams at that time.  Teams such as Northwestern and Penn State were perceived as better opponents at the time the game was played, and the odds were skewed toward that effect.  This is the same thing as claiming a win over a ranked opponent because they were ranked at the time - even though they have several bad wins now.
I'm writing this not to be critical of Mr. Pavlick but to offer another option as to how to find this result.  A few years ago, Matt Dover over at Roll Bama Roll wrote a piece comparing strengths of schedule for top teams.  It is a fascinating read for anyone interested.  He compiled data over 4 years and found the win % of top-12 schools against schools of various rankings.  From these percentages he produced a table giving the probability of loss for teams based on how good each opponent is.  This is almost exactly how Mr. Pavlick found his, except we can use up-to-date rankings to find our results. 
Here is the table, modified for win% (As Dover gave it in loss%)

Opponent Ranked      0-12  Opponent Ranked      13-25 Opponent Ranked       26-52 Opponent Ranked      >52   
Home Neut Away Home Neut Away Home Neut Away Home Neut Away
68.0 50.0 32.0 72.3 76.0 58.3 86.3 92.9 83.5 99.3 100 99.3

I used (as Dover did in the origional article) FEI rankings because they rank all FBS schools.  There are issues with some of these rankings, but for the most part they are pretty fair (FEI gives Wisky and Mich State higher rankings than the BCS so it is fair to OSU in this exercise even though it has OSU ranked lower).  In Pavlick's forum post, he found the probability of OSU's current win streak to be 0.805% (massaged up to 3.72%).  By using the method given here, that probability is 8.1%.  Though that is significantly higher, it is impressive nonetheless.  Furthermore, the probability of OSU finishing the season undefeated from this point is 63.5%, and the probability of a win streak that long (against those opponents) is 5.1%
Another exercise to look at and discuss is the strength of schedules.  OSU has been raked over the coals and has looked to be left on the outside because the B10 is weak and their OOC schedule did them no favors.  Looking at this year alone, OSU's probability of going undefeated is 55.5% to this point and 35.2% for the whole year (assuming Mich St in the B10CG).
How does this stack up against the other top teams?
Bama has also been criticized for a weak schedule (I was among them earlier in the season) but Ole Miss playing well and Auburn's unexpected excellence has changed that a lot.  Bama's probability of being undefeated at this point is 22.3%.  The likelihood of them winning out (including an SECCG against Mizzou or SC) is 15.9% for a season-long odds of 3.54%.  This is by far the most difficult of the 4 teams I looked at.
Florida State had a 40.0% chance of being undefeated at this point, and after the 77.0% chance of the remaining schedule (assuming Duke in the ACCCG), have a total strength of schedule of 30.8%.
Baylor had a 68.6% chance of being undefeated at this point, and face a 50.0% chance of loss coming up, for a total schedule strength of 34.3%
One last chart to sum it up:

Team                                          % to date     % remaing    % total Schedule
Alabama 22.3 15.9 3.54
Florida State 40.0 77.0 30.8
Ohio State 55.5 63.5 35.2
Baylor 68.6 50.0 34.3


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