Milwaukee Journal, January 18, 1913:

While enjoying a spin on the Daytona Beach automobile speedway yesterday the motorcycle ridden by Lew Richie, pitcher for the Chicago Cubs, struck a soft spot in the same and the pitcher was thrown from the machine, which was wrecked.
...
Richie was stunned by his fall, while his face, legs and arms were badly scratched and bruised.

I haven’t found any specific citations, but it seems fairly likely the injuries from this wreck directly caused the end of ...