Short answers, pulled from the story.
Jerry Dior created the Major League Baseball logo while working for the marketing firm Sandgren & Murtha. He completed the entire design process within a single afternoon after receiving his commission that year.
Commissioner Bowie Kuhn introduced the new logo on the 21st of July 1969 during the Professional Baseball Centennial Celebration held in Washington DC. All on-field uniforms of MLB employees began displaying the emblem starting in the 1969 season.
Dior selected this specific shape because its ambiguity allowed the batter to be right- or left-handed and of any ethnic background. This deliberate vagueness became the defining strength of the final design.
The first official colors of the MLB Batter logo were royal blue, white, and red arranged from left to right. In 2019, dark blue replaced royal blue as one of the primary colors alongside white and red.
For many years two graphic designers claimed credit for creating the piece including Jerry Dior and James Sherman. ESPN writer Paul Lukas cleared up the confusion surrounding their claims in November 2008 when Sherman admitted he was unaware of the earlier logo.