One might think nothing of MusicTAP's recent listing of The Very Best of Billy Joel as coming from Legacy on November 9. The Long Island native has been compiled a lot - his first, double-sized greatest-hits compilation in 1985, a third volume in 1997, an entry in Legacy's Essential series and so on. Call it a hunch, but this author thinks there might be something to this set. For one, Amazon's list price for the compilation is $9.99, suggesting a single-disc set...and when you think about it,