From the Mattoon Journal-Gazette for September 11, 1950:
Belleville, Ill. — The final playoff round between Paducah and Centralia of the Mississippi-Ohio Valley League has been called off, Clarence “Dutch” Hoffman, the league president, announced Saturday. The cancellation was blamed on “poor playing weather.”
At the time Paducah was leading West Frankfort two games to none in their five game series, and Centralia had beaten Mattoon 3-1. Two Paducah-West Frankfort games were postponed because of rain.
League directors will meet to determine distribution of the $600 playoff purse, Hoffman said.
Compare the 1951 TSN Guide, on the same topic:
Playoffs — Centralia defeated Mattoon, three games to one; Paducah defeated West Frankfort, three games to none; final series called off because of bad weather, injuries, and military calls.
As you can see, the accounts actually disagree, both about the status of the Paducah/West Frankfort series and about the reason for the cancellation. Looking at the game reports for those which were actually played, it looks like the weather was sufficient reason to shut things down; it was wet and cold, and few were in the stands.