Indeed, one of the problems in comparing algorithm results for coreference is that such a large number of anaphors are covered by simple string matching, leaving only a small data set on which the lexical methods can differ.
strset v2n contains 331 of 477 cases (268 of which are assigned correctly by baselinestr v2n ), so that improvements by the other methods are confined to the set of the remaining 146 anaphors.