This appears to be a result of the posters use of the revisions feature combined with a glitch in the ratings systems related to how it calculates rating revisions and weekly ratings.
Basically the user posted a track edition in the old week, then posted a new revision in the current week. When the week expires all tracks get a ratings bonus which locks the rates in for the previous week. The system is now averaging rates across two weeks, so 5 and 0 which results in a rating of 2.5.