When the survivor calculator determines the values to populate in the SBR for a record, you want to eliminate any values that obviously do not represent the best value for the field. These are most likely default values that are used when the actual value of a field is unknown. When a filter is defined for a field and a system object contains an excluded value in that field, the survivor calculator ignores that value and uses a value from a different system record for the survivor calculator. If there is only one system record in the enterprise record and that system record contains an excluded value, the excluded value is used for the SBR since there is no other value to use.
As an example, if you define a SBR filter for FirstName to exclude the value “Baby” and an enterprise record contains two system records, one with a FirstName of “Baby” and one with a FirstName of “Joel”, then the value populated into the SBR is “Joel” regardless of how the survivor calculator is defined. If you have the same filter definition with an enterprise record that contains only one system record and the value of the FirstName is “Baby”, then the value populated into the SBR is “Baby”.