Have you ever wondered how
baseball's rules for an at-bat came about? Four balls to a
walk, three
strikes to an
out, and what's with the rules for
foul balls anyway? Why do
pitchers work from a
mound, and why is it the height it is? Well, wonder less, as I explain a little of the ancestry of these mongrel rules.
Pitching as it exists today began in 1884, when the rules changed to allow overhand pitching. Before then, under Alexander Cartwright's rules, pitching resembled cricket bowling far more than it did the modern practice. The pitcher was required to throw underhand, with a stiff wrist, and was supposed to throw the ball "for the bat", i.e. with the intent of allowing it to be put into play. The pitcher was required to release the ball from behind a line 45' from home plate, and he was allowed to take a running start if desired.
In 1858, the called strike was introduced to the game, and in 1863, the concept of the strike zone and a ball appeared. In 1863, the pitcher's box was created to curb the running starts that had become prevalent in pitching. The pitcher had to start and finish his delivery within the box. The front of the box started at 45'6" from home plate, and it was 12 feet by 4 feet. The pitcher was no longer allowed to take a step during his delivery, but could pitch from anywhere within the box. In 1867, the pitcher's box shrank to a six foot square, and the hitter was allowed to request a low or a high pitch. As you can imagine, in this phase of the game offense was dominant. Baseball gloves had yet to be developed, fielding was uniformly poor, and the pitcher's role was quite limited. The games resembled cricket matches, both in the scoring level and the length of games. Clearly, changes were in order.
In 1872, the requirements of a strict underhand delivery and a stiff wrist were removed; pitchers could now throw from a low sidearm delivery, and the curve ball became legal. In 1879, the number of balls to a walk was set at nine; the following year, it was reduced to eight. Also, beginning in 1880, catchers were required to catch a third strike on the fly in order to register a strikeout. These changes were an improvement, but it was still common for at-bats to run much longer than they do now.
In 1883, modern pitching began with the removal of the ban on overhand pitching. The following year, all restrictions on the pitcher's delivery motion were removed, and the requirement for a base on balls dropped to six balls. In 1887, the game moved further towards the modern rule set, with five balls becoming the requirement for a walk and the adoption of the hit batsman rule awarding a batter first base if he was hit by a pitch. For this season only, there were four strikes to an out; before and since, there have always been three.
In 1889, the ball and strike rules of today were first established--four balls to a walk, with the traditional three strikes to an out. This brought the pitches per at-bat down towards a reasonable number; in modern times, this is around 3.75 pitches per at-bat. In 1893, the distance for pitching was changed from 50 feet, which had been the front of one of the incarnations of the pitching box, to the modern distance of 60' 6", and the pitching rubber was introduced, with the pitcher being required to have his rear foot against the rubber slab until he released the ball. The rules regarding the pitching rubber persist, largely unchanged, in the modern game.
A foul bunt was classified as a strike beginning in 1894, and a foul tip was classified as a strike if caught beginning in 1895. Presumably these changes were made in order to prevent players from prolonging their at-bats through deliberate foul bunting or foul tips until the pitcher made a mistake.
The pitcher's mound originated shortly after overhand pitching was allowed. Some pitchers wanted to throw from an elevated position downhill (which makes perfect sense, if you've ever thrown a ball overhand). They convinced their groundskeepers to pile dirt inside the pitcher's box. In 1904, the rules committee finally officially acknowledged the existence of the pitcher's mound and limited its height to 15", relative to the bases and home plate. The mound would stay at this height until 1968. After the dominant pitching performances that year, most notably by Bob Gibson, the rules committee decided to lower the mound to 10" in order to reduce the dominance of pitchers. The change worked quite well, as offense in both leagues jumped significantly in 1969.
The history of baseball is not an exact field; reputable sources disagree on exactly when some of these changes occurred, and on how the sport evolved from the 1830's to the 1890's. Hopefully, this sheds some light on the subject. If you find any factual errors or think something is missing, /msg WRW with your corrections.
Sources: Roger Kahn, The Head Game; baseballalmanac.com