Who's Who in Baseball: 1991 provides a comprehensive statistical overview of the players active in Major League Baseball during the 1991 season. This reference work details individual player statistics, career achievements, and biographical information for a wide range of baseball figures. It serves as a historical record for fans, analysts, and historians seeking detailed data from that specific year in baseball.

This edition of 'Who's Who in Baseball' is a factual compilation intended for dedicated followers of the sport. The value lies in its detailed statistical data and player profiles from a specific year. It functions as a historical archive, offering insights into the performance and careers of the players active in 1991.