It’s All In The Numbers

In a recent RPI Poll, Southern Miss is ranked twelfth nationally and Ole Miss is thirty-fourth. How can that be, after-all Ole Miss is ranked twentieth in the most recent AP Poll and Southern Miss is not even ranked. To top it off, Ole Miss (8-1) is responsible for Southern Miss’ (6-1) only loss of the season.

On December 5th, the Rebels rallied from six down with a minute to go to stun Southern Miss 81-79. Eniel Polynice’s slam dunk with a second to go in regulation gave the Rebels the victory.

I understand the RPI Poll and the AP Poll are separate and that the AP Poll does not calculate into the RPI Ranking. I believe both Ole Miss and Southern Miss have strong programs this season. I’m just trying to better understand the numbers, because of the information I mentioned above, at first glance the RPI rankings appear to be a misprint.

So what is an RPI? In college basketball the acronym stands for Ratings Percentage Index. It is a formula that calculates just how strong a team is.

How important is the RPI? Important enough that the NCAA tournament selection committee uses the RPI to help determine the NCAA tournament field and seeds.

If you are like me, you believe in the numbers. So I thought I would throw out so interesting statistics provided by “The RPI Report.“ The numbers in this next paragraph prove just how influential the RPI is.

Since 1991, 99.3% of teams ranked No. 1-30 in the RPI have been in the NCAA tournament as both automatic and at-large selections, 83.1% ranked No. 31-40 in the RPI were in, 55.4% of the teams ranked No. 41-50 in the RPI played in the tournament, 25.7% ranked No. 51-60 were in it, and only 9 at-large teams ranked below No. 60 have been selected for the tournament. While the NCAA says that they do not use the RPI directly for selecting teams for the tournament, it is obvious that the better the RPI rank, the better chance a team has for making the tournament.

I already know you’re next question. It’s the same one I would ask. What makes up the RPI formula? The RPI formula uses team winning percentage (25%), opponent winning percentage (50%), and a strength of schedule proxy (25%) to create a single numerical performance rating.

Now that we understand what the RPI is and how it’s calculated, it’s time to revert back to my original question. How is Southern Miss ahead of Ole Miss in the RPI?

Without actually doing the calculations, at first glance it seems obvious that Ole Miss should be rated higher than Southern Miss. Lets take a closer look at what appears to be so obvious to me.

Let’s start with winning percentage and remember this category counts for twenty-five percent of the formula. I’ve already established both teams have just one loss and the Rebels won the head-to-head battle. The Rebels also have two more wins on the season compared to Southern Miss. Again at first glance, it appears the Rebels should be rated higher.

Opponents winning percentage makes up fifty percent of the formula and strength of schedule is twenty five percent. That’s seventy-five percent of the formula. When I look at who both teams have played so far, there is one thing that really jumps out at me. The opponents on both teams schedules.

How important is it for a team’s opponent to be from the Division one competition level when calculating the formula?  I would assume if you’re opponent is not competing at the Division One level, they would be considered low when it comes to strength of schedule (25% of the formula). However, it is possible for a non division one opponent to have a strong win-loss record (winning percentage counts for 50%). So does an opponent not competing at the division one level calculate into your RPI formula? The answer is no.

The only teams calculated in the RPI formula are other division one teams that have an RPI rating. There are 347 schools with an RPI. Are you still with me? I know this appears to be confusing, but there is still something else that jumps out at me.

We have established that you must play strong opponents and you must win games. This is what is jumping out at me as a red flag. Three of Southern Miss’ six wins are against NAIA schools (Loyola (New Orleans), William Carey, and Spring Hill). The Golden Eagles have yet to play Dillard, a fourth NAIA school on their schedule. That means Southern Miss is actually just 3-1 against other RPI schools. Ole Miss, on the other hand is 8-1 and the only schools on their schedule are RPI schools.

As mentioned earlier, a team’s winning percentage and strength of schedule count for twenty-five percent each or fifty percent of the RPI collectively. At first glance, I would think an 8-1 record compared to 3-1 would make Ole Miss a stronger team than Southern Miss, but remember there’s that other fifty percent of the calculation to consider (opponents winning percentage).

So let’s take a closer look at the opponents winning percentage category. I thought I’d make things easier on you and provide a snapshot of exactly who Ole Miss and Southern Miss have played up to this point of the season. The first number in the parenthesis represents a team’s overall win-loss record. The second number is a team’s win-loss record versus RPI teams on their schedule.

Ole Miss has only one loss on their schedule and that is to Villanova (9-1, 9-1). The Rebels have beaten the following RPI teams: Arkansas-Little Rock (4-6, 2-6), Alabama State (1-6, 0-6), Indiana (4-5, 4-5), Kansas State (9-1, 8-1), Texas A&M-CC (4-4, 2-4),Arkansas State (3-5, 2-5), Southern Miss (6-1, 3-1), and McNeesee State (3-5, 1-5).

Southern Miss has only one loss and as previously mentioned it is to 8-1 Ole Miss. And as another friendly reminder, all of the Rebels wins are against RPI teams.

Here are the RPI teams the Golden Eagles have beaten so far this season.(Montana State (5-4, 3-4), Louisiana Lafayette (3-4, 2-3) and South Alabama (7-3, 4-3).

At first glance it appears Ole Miss should be rated higher than Southern Miss in the RPI, but again an opponent’s winning percentage counts for fifty percent of the formula. That fifty percent plays a crucial role and when the final numbers are crunched Southern Miss is ranked twelfth in the nation and Ole Miss is thirty-fourth. It just goes to show you that when it comes to the RPI don’t go by first glance because the proof is in the numbers.

We are not even out of December and I’m already excited for the NCAA tournament. Let the Madness begin.