I have always been fascinated by defunct rules since some are quite unusual. Until 1950, a courtesy runner was allowed if a player had been injured and couldn't continue temporarily. The replacement runner had to be approved by the opposing manager and did not count as an official substitution. Therefore, the option remained for the injured or otherwise incapacitated individual to return to his post in the next frame. Likewise, courtesy runners were free to resume their normal responsibilities once they had completed their obligation on the basepaths. The last courtesy runner appeared in the majors during the 1949 campaign. The rule created some interesting scenarios.
In a June contest during the 1949 slate, Joe Gordon of the Indians hit a grand slam in the first inning off of Red Sox starter Joe Dobson, making the score 5-0 with no outs. As a retaliatory gesture, Dobson beaned Lou Boudreau. Boudreau was replaced with Ken Keltner, who had just scored moments before on the grand slam. Dobson walked the next batter and exited the game without retiring any of his opponents. Keltner then scored his second run in a short span on a single by Bob Feller. In the bottom of the frame, Keltner and Boudreau returned to their respective stations.
In a nineteenth century contest between Boston and Washington, Al Maul of the Senators was hit by a pitch leading off the third innning. Injured, catcher Deacon McGuire ran for him. Since McGuire was no speed demon, Beaneaters Manager Frank Selee gave the substitution his stamp of approval. Despite being relatively slow afoot, McGuire moved to second on a walk, then stole third base. He later scored on a triple and returned to the dugout to immediately take his rightful turn at bat.
Though this final anecdote has nothing to do with courtesy runners, it does relate to multi-tasking players. In a story popularized by Babe Ruth (which immediately makes it somewhat suspect),
outfielder Bobby “Braggo” Roth was asked to stand-in as a third base coach one
day when a member of the Yankee staff was ejected for arguing a call. With a
man on first, the next batter laced a double into the gap. Although a run could
easily have scored, Roth put up the stop sign, holding his teammate at third.
He then jogged quickly to the dugout, drawing baleful stares from other
players. “Why didn’t you send him in?” An exasperated Ruth wanted to know.
“What?” Roth said unabashedly, grabbing a bat, “With me coming up next?”