I have encountered the word pigeon in connection with tennis players, for example, have a look here, here or here. It seems to be a slang term - at least I did not find it in any news article.
From the context it is clear that it has something to do with one player having bad H2H against another player. Could somebody give a clearer explanation when this word is used? Etymology of this phrase could also bit interesting. Has this originated from some common idiom in English?