The uncaught third strike, or sometimes called the dropped third strike, is a rule in baseball involving the catcher. If the catcher fails to make a clean catch on a pitch that is a recorded third strike (the batter swung and missed the ball or the ball was in the strike zone) and the ball touches the ground, the runner may run to first so long as there is not a baserunner already there. The batter must be either tagged out or forced out by a throw to first base.
In the case of a runner on first base with two outs, an uncaught third strike results in the batter becoming an active runner as well. Regardless of the result of an uncaught third strike, the pitcher and batter are both recorded a strikeout.
Though not necessarily a rule, tie goes to the runner is a very popular interpretation of the out rules in Baseball. In Baseball, a runner is called out if they or first base is tagged with the ball before the runner reaches the base. In close-play scenarios where it appears that the runner and the ball reach the base at the same time, umpires generally give advantage to the runner. This interpretation of the rules is often widely discussed among baseball officials.
This rule is also very similar to the simultaneous possession rule in the NFL, which is often also widely disputed and controversial.
The infield fly rule is quite possibly the most controversial rule in baseball. The infield fly rule is a rule that allows the on-field umpires to call a batter/runner out if they hit a fly ball in the infield with players on first and second or with the bases loaded. In this situation, the batter who hit the ball is automatically out while the players on base can remain on base. The infield fly rule is never called with two outs and the fielding team must record the third out, either by catching the fly ball or tagging a runner.
This rule is in place to protect the batting team. For example, the player fielding the ball could purposely drop the ball, then throw the ball to third for the start of a double, or even a triple, play. However, many dislike this rule as it results in a guaranteed out when the fielder playing the ball could drop the ball, which would result in the batter being safe at first if an infield fly were not called.
A balk occurs when a pitcher performs an illegal motion, usually pretending to pitch the baseball without actually meaning to perform a pitch. If a pitcher performs one of these motions, which includes pretending to throw the ball but holding it instead, unnecessarily delaying the game, pitching away from the batter, throwing to a fielder who is not on a base, etc. then a balk will be called.
A balk results in an immediate dead ball. If there are any runners on base, they advance one base forward. The batter stays at bat and maintains the same count. Balks rarely occur, but can occur when a pitcher gets into a stressful situation that may cause them to make a mistake.
An automatic strike may be more rare than a balk! An automatic strike occurs when one of three things occurs: the batter refuses to take position in the batter's box, the batter leaves the batter's box while the pitch is on its way from the pitcher, or the batter hits the catcher with their bat due to negligent swinging. If any of these occur, the batter can be given an automatic strike, which is added to the count of the current at-bat.
The 'pinch' substitution rule is one fairly unique to the sport of baseball. At any time, a team may substitute a player currently in the game with another player who is not in the game. This includes substituting the current batter with a pinch hitter, or a baserunner with a pinch runner.
Unlike other sports, the player being subbed out of the game cannot re-enter the game at any time. The player being subbed into the game assumes the role of the player being subbed out, which includes their spot in the batting lineup and their fielding position. Of course, this can also be swapped when a manager discusses the change with the head umpire.
Players in uniform are not allowed to fraternize with members of the opposing team, as well as members of the audience. There is not much explanation to this rule, though it is rarely enforced.
The ambidextrous pitcher rule was added when pitcher Pat Venditte joined the MLB. Venditte is an ambidextrous pitcher, but umpires had a difficult time determining what to do when Venditte faced a switch-hitter. The batter did not want to bat on the left side if Venditte was going to pitch left handed and vice-versa. The MLB declared the ambidextrous pitcher rule, in which the pitcher must declare what hand they're going to pitch with for the at-bat. The batter may then decide which side of the plate they're going to bat from. The pitcher may not switch hands until the at-bat is complete, in which they may switch hands before the next batter after notifying the umpire.
Another rarely enforced rule is the 12-second rule, in which the pitcher must pitch the ball within 12-seconds after receiving the baseball if there are no runners on base. The MLB also instituted a 20-second pitch timer in the 2019 spring training in an effort to speed the game up. Failing to abide by the pitch timer results in a ball being called for the batter.
A ground rule double occurs when a ball is fairly hit and lands in the field of play, but then leaves the field of play without interference from a fielder. This occurs most often when a batter hits the ball near the sideline in fair territory, then the ball bounces out. In case of a ground rule double, the batter is awarded a double and any runner on base advances one base. This occurs often in parks that have sidelines very close to the foul lines.