Thanks, jmc44!
Here are your 25 calendar dates:
January 7, 2019 Eric Gagne
January 10, 2019 Willie McCovey
January 15, 2019 Rance Mulliniks
February 4, 2019 Possum Whitted
February 6, 2019 Babe Ruth
February 19, 2019 Tim Burke
March 19, 2019 Clayton Kershaw
March 25, 2019 Kirby Yates
April 13, 2019 Claude Hendrix
May 11, 2019 Charlie Gehringer
May 18, 2019 Babe Adams
May 22, 2019 Al Simmons
June 12, 2019 Hideki Matsui
June 17, 2019 Dave Concepcion
June 23, 2019 Tim Anderson
June 29, 2019 Harmon Killebrew
July 7, 2019 Satchel Paige
July 15, 2019 Bubbles Hargrave
August 17, 2019 Jorge Posada
August 27, 2019 Jim Thome
September 23, 2019 Trevor May
October 28, 2019 Frank Smith
November 12, 2019 Joe Hoerner
November 20, 2019 Gabe White
December 9, 2019 Joe Kelley
They were picked randomly out of 365 possible dates between January 1, 2019 and December 31, 2019.