A Baseball Historian/Expert needed for this question

There was a baseball pitcher who played for the Pittsburgh Stogies in the old Federal League from 1912-1914. He was known as Mysterious Walker.

My question is: How did he earn the name Mysterious? Thank you in advance for your answer(s).

Can’t help you with the nickname, but I can tell you that the Federal League only existed in 1914 and 1915. Walker pitched for Pittsburgh in 1914 and Brooklyn in 1915.

Fredrick Mitchell,“Mysterious” Walker

ERa 4.31


Source of nickname unk.

I can only imagine what the Stogies mascot looked like.

(“Hey… gotta light?”)

B.1884,Utica, Nebrasks

D.1958,Oak Park Illinois

1910 Cincinnati–nat

1912 Cleveland amer

1913 Bklyn nat

1914 Pittsburg nat

1915 Bklyn nat

According to a 1987 NYT article by Ira Berkow, Mysterious Walker had a penchant for disappearing from his team for long stretches of time.

Note his itinerant career.