[BostonCard]

Yes, Hulk; it is the fact that they play in the SEC.  At an extreme, consider a team that loses every game against teams with a perfect records.  They would get 0 for their record and .5 for their opponent's records (let's leave out the opponent's opponent's record).  In contrast, a team with a perfect record against winless teams gets .25 for their own record and 0 for their opponents.

The only real virtue of RPI is that it is fairly easy to calculate and transparent.  But it is a bad model for determining how good a team is.

If I were creating a simple system, for every win, you add the opponent's winning percentage and divide by a tally of your losses against 1 - the opponent's winning percentage (that is, their losing percentage).  Consider the following team:

result	opponent record	points
W	7-3	+0.7
W	6-4	+0.6
L	8-2	-0.2
W	4-6	+0.4
L	2-8	-0.8

That gives you an effective record of 1.7 points for wins versus 1 point for losses, a modified RPI of .629.  You could further this by doing a second order calculation.

The conventional RPI would give the team the following
record: 3-2, 0.6 (worth 25%)
opp record: 27-23, 0.54 (worth 50%)
opp opp record (depends, but probably will cluster around 0.5, worth 25%)

overall RPI .545

BC

[BostonCard]

Yes, Hulk; it is the fact that they play in the SEC.  At an extreme, consider a team that loses every game against teams with a perfect records.  They would get 0 for their record and .5 for their opponent's records (let's leave out the opponent's opponent's record).  In contrast, a team with a perfect record against winless teams gets .25 for their own record and 0 for their opponents.

The only real virtue of RPI is that it is fairly easy to calculate and transparent.  But it is a bad model for determining how good a team is.

If I were creating a simple system, for every win, you add the opponent's winning percentage and divide by a tally of your losses against 1 - the opponent's winning percentage (that is, their losing percentage).  Consider the following team:

result	opponent record	points
W	7-3	+0.7
W	6-4	+0.6
L	8-2	-0.2
W	4-6	+0.4
L	2-8	-0.8

That gives you an effective record of 1.7 points for wins versus 1 point for losses, a modified RPI of .629.  You could further this by doing a second order calculation.

The conventional RPI would give the team the following
record: 3-2, 0.6 (worth 25%)
opp record: 27-23, 0.54 (worth 50%)
opp opp record (depends, but probably will cluster around 0.5, worth 25%)

overall RPI .545

BC