EvilLyrics visits lyrics sites in order determined by search engines. If it returns site YYY as having required lyrics we will visit this site first.
This happens usually when it looks for new lyrics, which may first appear at smaller lyrics sites or they are first spotted and indexed by search engines.
Other reason if misspelled name. Popular site XXX contains all the lyrics from Britney Spears but only site YYY has lyrics for Brittany Spaers, if this is how you mp3 file is named.