Hal Kelleher pitched a four-hit shutout in his MLB debut on September 7, 1935. Less than three years later, on May 5, 1938, Kelleher set a baseball record by giving up 12 runs in a single inning in what would become the final game of his major league career.
Under what circumstances would a manager allow a pitcher to take that kind of beating? Well, the Phillies started the season 3-12 record and trailed by eight as they took the field in the bottom of the eighth with the Cubs' 2-4 hitters coming up. Manager Jimmie Wilson just let Kelleher try to work through it. By the time it was over Kelleher had given up 10 hits and walked three batters.
At the time, it must have felt normal for everyone involved. The '38 Phillies were part of a historically bad run. Coming into the year the Phillies had experienced just one winning season in the previous two decades. Starting in 1938 and running through 1945, the franchise posted five of the worst seasons in the history of baseball. Of the 24 worst seasons (by win percentage) in baseball's modern era, five of those seasons belong to the World War II era Phillies.
Someone from that run had to do something historically noteworthy in an unfortunate way and it happened to be Kelleher, who would never pitch in the big leagues again.
According to Baseball-Reference, Kelleher was purchased by the St. Louis Cardinals three weeks later and he spent a short time in their system before taking a break. Despite a brief comeback in 1944 and 1945 in the Brooklyn Dodgers' minor league system, Kelleher's professional baseball career was over.
In 1940 he became a police offer in South Philadelphia. (He also worked at Pep Boys at some point during that era.) During his time with Philadelphia police he became a supervisor of the Police Athletic League and even worked as an athletic trainer at La Salle University.