Computer rankings can be subject to dispute. That is true. Inasmuch as different computer rankings will produce different results, the fact that they are not perfect cannot be denied. If perfection were possible, it would be represented by only one result. However, in my opinion it is not correct to suggest computer rankings have little or no practical value when rating teams in closed conferences, and then ranking them amongst teams from other conferences.
The formulas used by the computers are very sophisticated. The rankings will be less accurate overall when dealing with closed conferences because there are no interconference games by which to measure conference strength. That is true for the current season until such time as the playoffs begin. Nevertheless, the computer systems do measure conference strength, and do so in a reasonably accurate manner. It is done by measuring conference performance during playoffs in previous years. The results of these games are generally weighted more heavily than regular-season games because of their relative scarcity; and playoff results from more recent years are weighted more heavily than results from years further in the past. The outcome is that the best team in some closed conferences will have a considerably better ranking than the best team in other closed conferences.
As you know, the Fox Valley Conference is a closed conference. The average (mean) Massey rating of the ten teams in the Fox Valley Conference is 30.309. The Big Northern Conference is also closed. The average Massey rating of its ten teams is 7.442. This difference demonstrates the Massey computer rankings do measure conference strength.
The following example provides another demonstration. Prairie Ridge (4-1) is one of three teams currently tied for first place in the Fox Valley. South Elgin (5-0) is one of two teams tied for first in the Upstate Eight, another closed conference. When using the matchup tool, Massey has Prairie Ridge as a 17-point favorite over South Elgin on a neutral field.
Although closed conferences make the task a little bit more difficult, and the results a little bit less accurate, computer rankings can be used effectively to seed teams for playoffs even when closed conferences are involved.