The context of the song ("piazza, new york catcher" is:
The catcher hits for .318 and catches every day
The pitcher puts religion first and rests on holidays
He goes into cathedrals and lies prostrate on the floor
He knows the drink affects his speed, he�s praying for
a doorway
Back into the life he wants and the confession of the bench
Life outside the diamond is a wrench
The "diamond" refers to the playing field of baseball. The meaning as I see it, is that when these baseball players are not actually playing the game in front of fans, away from the exitement, life for them has the same problems of any normal person.
"Piazza" refers to Mike Piazza - a catcher for American baseball New York Mets.