A Baseball Historian/Expert needed for this question

Factual Questions
1

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).

2

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.

3

Fredrick Mitchell,“Mysterious” Walker

ERa 4.31

!914

Source of nickname unk.

4

I can only imagine what the Stogies mascot looked like.

(“Hey… gotta light?”)

5

B.1884,Utica, Nebrasks

D.1958,Oak Park Illinois

1910 Cincinnati–nat

1912 Cleveland amer

1913 Bklyn nat

1914 Pittsburg nat

1915 Bklyn nat

6

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.