imho all elo-like systems fail hard when you don't know the rating of newcomers and/or you don't adjust it really quick, because the whole system of comparing rating values is based on the assumption that those ratings are correct, and reflect really a player's skill.

In chess elo it's not a big problem, in et with all the renaming and stuff it gets huge... I don't know how tb deals with the problem of new nickname's initial rating, maybe making a 'standard' fixed average rating would probably lead to less trouble, since after all the average skill of pub players is generally the same ('bit higher on etpro servers actually, but nobody rates on etpro so...)

A newcomer (new nick) should start with a rating similar to his real skill, otherwise = system fail