VORP is "an estimate of each player's overall contribution to the team, measured vs. what a theoretical "replacement player" would provide, where the "replacement player" is defined as a player on minimum salary or not a normal member of a team's rotation."
I scored 140/200, but it is interesting that the players before 1970 are left out. But the source does say "BPM (OBPM/DBPM) and VORP are calculated for seasons 1973-74 until present". Thanks for the quiz!