Frank Taveras came into OOTP 1971 as a free agent rather than being assigned to the Pirates. He was drafted by the White Sox.
Real Stats in OOTP show his debut year as 1972. As can be seen from the game stats his debut in OOTP was 1971.
The problem appears to be related to OOTP not having his 1971 stats. They may be missing because (according to Baseball Reference stats) there were no plate appearances or field appearances. He appeared in one game as a PR.
Here's the BR link
https://www.baseball-reference.com/p...averfr01.shtml