I really don't think of Johnny Bench listening to disco. Yes, he was of the Disco Era, but I also don't see him as a Dandy.
If I had to match musical tastes with these six players I would do it this way:
Mike Schmidt - BTO, Kansas, Paul McCartney and Wings
Johnny Bench - Elton John, Hall & Oates, John Denver
Lou Brock - Diana Ross, Lou Rawls, Commodores
Reggie Jackson - Rick James, Chic, Rose Royce
Willie Stargell - Booker T and the MGs, Earth, Wind and Fire
Tom Seaver - Eagles, Bee Gees, Abba