Sure, these rules seem obvious—but in days past, they were challenged enough that officials added them to the rulebooks anyway.
1. Runners cannot run the bases backwards [Rule 7.01, 7.02, 7.08(i)]
Considering the purpose of a baserunner is to advance safely to home plate, running the bases in reverse seems nonsensical. However, the silly antics of Germany Schaefer, a journeyman infielder in the early 1900s, forced officials to put this rule in the book.
On August 4, 1911, Schaefer stole second, intending to draw a throw from the catcher to allow his teammate—Clyde Milan, who was on third—to steal home. However, the opposing catcher held the ball, keeping Milan struck at third. Hoping to recreate the play, Schaefer looked to steal again. This time, the only option was to steal first.
On the next pitch, he took off for first, but a double steal still didn't materialize; the catcher was too surprised to make the throw. The opposing player-manager ran onto the field to argue and amid the chaos Milan finally took off for home plate, where he was thrown out.
This wasn't the first time Schaefer attempted a double steal by regression, but the 1911 stunt received more publicity. It took until 1920, but the sport's officials finally passed a rule prohibiting such actions, which remains to this day. Now, if a player runs the bases in reverse order, he is automatically out.
2. No substitutions may be made while the ball is in play [Rule 3.03]
Rule 3.03 clearly states that substitutions can only take place when the ball is dead, prompting the question of why anyone would think to change players in the chaos of live action. The rule was instituted after an alert play by Michael Joseph “King” Kelly, a popular catcher-outfielder in the 1880s.
While he was sitting on the bench one day in 1891, an opposing batter hit a high foul ball that Kelly immediately recognized would be out of the reach of all of his teammates. Kelly, a player-manager, quickly jumped up and went after it, calling “Kelly now catching!” He made the catch, but the umpire refused to call the out. Kelly argued that the play was not against the rules, which at the time stated that substitutions could be made at any time.
That winter, the rules were changed to officially prevent such a play.
3. Umpires are prohibited from conferring with players or spectators [Rule 9.04(c)]
While the home team probably embraced such conferences with wide-eyed innocence (“What, our fans could make a biased call? Never!”), baseball officially banned umpires from conferring with players or people in the crowd in 1882. The rule overturned one from 1876 that allowed an umpire to confer with whomever he pleased if he or she had been unable to see a play. The practice of employing only a single umpire had necessitated such a rule. By 1882, however, the idea of a staff of umpires was becoming more popular, negating the need for assistance from players or fans. Presumably, the type of assistance spectators offered also probably did little to help matters.
4. Runners must touch each base [Rule 7.02, 7.04(d)]
It is not unusual to see ballplayers called out for failing to touch a base before advancing, and few fans would question why they are required to do so in the first place. Before the Civil War, that was only an unofficial requirement, and base runners did their best to take advantage of it. What started as just cutting corners soon devolved into making little effort to get near the bag at all when legging out an extra base hit. In 1864, the requirement became an official rule.
5. Base coaches are prohibited from running the bases while the ball is in play [Rule: 4.05(b)]
In the early days of the game, teams often tried to make fielders mistake a base coach for a runner. For example, in an 1886 game against Detroit, Chicago base coach Mike Kelly ran out to the shortstop position to provide a distraction for his runner. The introduction of coaches’ boxes the following year helped curb the tactic, but they failed to entirely eliminate it.
In 1890, George Smith, coaching for Brooklyn, ran down the third baseline in front of his runner, causing the catcher to mistakenly tag him while the baserunner slid in safely. After a long argument, the umpire ruled the baserunner out. A 1904 rule change finally prohibited the practice altogether.
6. An umpire is permitted to put a new baseball in play whenever he deems it necessary [Rule 3.01(e)]
In an era where major league teams go through nearly 1 million baseballs in a season, spelling this out seems completely unnecessary. In 1886, however, the idea was revolutionary. Prior to that year, the umpire had to give the teams five minutes to find a lost ball before he could supply a new one. Some especially frugal owners were unwilling to pay for the expense of a new ball and insisted that the search continue until the original ball was found.
While the wording has shifted some in the modern era, the rules still stipulate that the umpire has access to a supply of alternate balls that will last for the whole game, implying the umpire’s power to introduce them into play.
7. A fielder is not permitted to catch a ball with his cap [Rule 7.04(e), 7.05]
Although it's in place to keep fielders from using caps and other articles of clothing to make catches, this rule had to undergo various changes so it wouldn't be an advantage to the defensive team. The 1857 rules stated that if a player caught a ball with his cap, no opposing player could be put out until the pitcher had touched the ball.
The Boston Red Stockings turned this rule to their advantage on September 14, 1872, when the opposing team loaded the bases with no one out. The batter hit an easy popup to Boston shortstop George Wright, who deftly caught the ball with his cap, then tossed it to his pitcher. The pitcher threw it to the catcher, who tagged home plate and threw to third. Boston then applied tags to third base and second base before their opponents realized what was happening.
Although the Red Stockings argued for a triple play, the umpire refused to count the play at all. A clearer rule was established in 1873 and modified in 1874. Now, the runner is awarded the base if a fielder catches the ball with his cap.
8. Fielders are prohibited from doing jumping jacks while an opponent is batting [Rule 4.06(b)]
After Boston Braves batter Bob Elliott asked the second base umpire to move out of his line of vision on August 9, 1950, Giants second baseman Eddie Stanky saw the opportunity for a new distracting ploy. He moved to where the umpire had been standing and began to pace around, waving his arms and jumping up and down. He continued practicing his antics in subsequent games until umpires appealed to National League President Ford Frick, requesting a ruling on the legality of such actions.
Arguments for both sides became heated, until those against the practice expressed concern for the safety of hitters who become distracted during a pitch. Frick instructed umpires to eject fielders who employed jumping jacks or other annoying antics to distract the batsman, and his decision is preserved in the official rulebook to this day.
9. A batter was prohibited from deliberately striking out [Rule: 2.00]
The Sporting News called a deliberate strikeout on a wild pitch “one of the smartest schemes” in baseball at the turn of the 20th century. According to rules that are still in place, a batter becomes a runner that must be tagged or thrown out in the event of a swinging strikeout on a wild pitch. In an 1894 Southern League game, Abner Powell made it safely to second base after taking a mighty swing at a pitch he saw was going to go behind his back. The vast amount of foul territory behind home plate allowed the runner to take multiple bases before the catcher could collect the errant pitch. Eleven years later, in a Major League game between Detroit and Cleveland, Cleveland hitter Bill Bradley did the same thing. Before Detroit catcher Lew Drill could recover a pitch that sailed ten feet wide of the plate, Bradley had made it safely to second base.
A set of rules for baseball in 1868 and 1872 prohibited “willfully strik[ing] at balls for the purpose of striking out.” While no longer specifically banned, the official rules still address such a situation in Rule 2.00. However, getting to second base on a swinging strike three would be difficult in modern ballparks, since the amount of foul territory behind home plate has been vastly reduced in an effort to get fans closer to the game.
10. Baserunners are not permitted to continue running after they have been called out [Rule 7.09]
On June 17, 1926, the Cubs loaded the bases against Brooklyn in the sixth inning with one out. With right fielder Jimmy Cooney on first, Joe Kelly hit a grounder to Brooklyn first baseman Babe Herman, who threw it to his shortstop, Rabbit Maranville, to begin the double play. Maranville’s return throw was wild, however, and the Chicago runners continued to advance. The Brooklyn pitcher retrieved the ball and tried to gun down the runner he saw heading toward home plate. The runner peeled off for his dugout before he reached the plate, forcing the catcher, Mickey O’Neil, to follow him to apply the tag for the third out.
That runner, however, was none other than Jimmy Cooney, who had been the second out of the inning. The home plate umpire could think of nothing in the rules that prohibited such a play, and he ruled that the inning must continue. Cooney’s ploy had allowed Kelly to advance to third, and Chicago tacked on two more runs that inning.
No sportswriter of the era could recall a similar play, and it would fall under questionable legality today. Rule 7.09 stipulates that no member of the offensive team can take actions to confuse, hinder, or impede the fielders, but also stresses that a runner continuing to advance after being called out cannot by that act alone be called for interference. The result of such a play today, then, would depend entirely on the umpires’ judgment.
11. Fielders are prohibited from throwing potatoes or other objects while the ball is in play [Rule 9.01(c)]
From the early days of the sport, players have tried to deceive base runners through a plethora of tricks. One common example was when basemen would wildly throw small white objects to trick runners into thinking they had thrown the ball away. They would then calmly tag the runner with the real ball if he was deceived and left the base.
Potatoes, especially those peeled, frozen, and whitewashed, were a favorite. Umpires never tolerated the trick, even when players went to great lengths to excuse it. A catcher in the Evangeline League in 1934 tagged two runners out who tried to score after he launched a potato into the outfield, but the umpire called them safe and refused to accept his explanation that he had simply found the potato and was trying to get it off the field of play. An 1889 member of the Staten Island Athletic Club learned the hard way that the hidden-potato trick was not allowed in college ball, either, when he was asked to resign from the club after he employed the ruse and the umpire ruled the runner safe in a game against Yale.
Minor league catcher Dave Bresnahan tried to revive the old trick on August 31, 1987, but the umpire ruled the runner safe. The next day, the Indians fined and then released Bresnahan. While nothing in the rulebook actually prohibits throwing potatoes, each time it has occurred, the umpires have ruled it to be illegal under rule 9.01(c), which allows umpires to make a ruling for anything not covered in the rulebook.
12. Fielders are not permitted to blow a ball foul [Rule 9.01(c)]
In a 2012 Spring Training game, Los Angeles Dodgers third baseman Jerry Hairston fell to his knees and attempted to blow a slow dribbler foul. His attempt was unsuccessful, but sportswriters immediately harkened back to a similar play Seattle third baseman Lenny Randle had made on May 28, 1981.
Randle successfully blew the ball into foul territory and Larry McCoy, the home plate umpire, called the ball foul, but reversed his decision after Kansas City manager Jim Frey argued. Evoking his powers from rule 9.01(c), he declared that Randle had illegally altered the course of the ball. His ruling set a precedent, making the play unofficially illegal ever since.
Randle had not been the first to try such a stunt, though. Bert Haas, a member of the Montreal Royals of the International League, had tried the same thing on a suicide squeeze in a 1940 game. When Haas realized he would not be able to throw out either runner, he began his efforts to blow the ball. Just before the ball reached third base, it rolled foul. The umpire ruled the runner had to return to third and the batter back to the plate. Strangely, the opposing team did not protest the decision. After the game, however, International League President Frank Shaughnessy issued a statement that no player would be permitted to blow a ball foul after that.
While knowledge of Shaughnessy’s ruling may have spared Randle the inclusion in many sports blooper reels, McCoy’s 1981 ruling set a precedent at the Major League level that such a play would not be tolerated today, even though it is not in the rule book.
Additional sources: The Giant Book of Strange but True Sports Stories; A Game of Inches: The Stories Behind the Innovations that Shaped Baseball: The Game Behind the Scenes (Vol. 2); Baseball Almanac.