From BR Bullpen
A spitball (aka spitter, wet one, or unsanitary pitch) is a pitch in which the pitcher applies saliva to the baseball, either to change its aerodynamic properties or to reduce friction between his fingers and the ball. The term is sometimes applied loosely to pitches in which the ball is treated with other foreign substance, such as vaseline, and occasionally to any type of pitch that involves doctoring the baseball. The spitball rose to prominence in the early 1900s and was widely used into the 1910s. It, and all other pitches involving doctoring the ball, was banned before the 1920 season, though some "bona fide" spitball pitchers were allowed to continue throwing the pitch for the remainder of their careers. Many pitchers since have been accused of throwing spitballs illegally, and a few were either caught or admitted to doing so after retiring.
It is unclear when pitchers first began experimenting with the spitball, but there is no evidence that any pitcher made it an important part of his pitching arsenal before 1902. The spitball has often been credited to Elmer Stricklett. Stricklett did not invent the spitter- he learned it from minor league teammate George Hildebrand, who had learned it from his minor league teammate Frank Corridon - but he had a key role in introducing it to the majors. While both Hildebrand and Corridon used it in the majors, Jack Chesbro and Ed Walsh were the first star pitchers who depended heavily on the spitball, first learning about it by watching Stricklett. The tremendous success of Chesbro and Walsh- the only American League pitchers ever to win 40 games in a season- led other pitchers to take up the pitch, and it quickly became common.
The legality and ethics of the spitball were always questionable. Rules dating back to the 1890s forbid players from discoloring or "otherwise damaging" the ball, which might or might not cover applying spit. The situation became worse when Russ Ford discovered that he could create a devastating pitch by scuffing the ball with emery paper, and other pitchers quickly followed suit. The questionable spitball had opened the door for the clearly illegal emery ball and similar pitches. Even though defacing the ball was clearly illegal, pitchers continued to do so because the rule was weak- the only penalty for being caught was a $5 fine- and rarely enforced. In many cases the pitcher didn't need to scuff the ball because the rules allowed balls to remain in play after they had been damaged and discolored by ordinary use.
For the 1920 season, the leagues finally decided to crack down. The spitball and other defaced ball pitches were banned. Any player caught defacing the ball would be expelled from the game, and any pitcher caught pitching a defaced ball was subject to a 10 game suspension. An exception was made for up to two pitchers on each team, who would be allowed to throw spitballs but no other kind of defaced ball pitch. While the exemption was originally intended to last for just one season, the leagues backed off slightly after the season. They identified 17 "bona fide" spitball pitchers who were allowed to continue throwing the spitball for the remainder of their careers. The last of these "grandfathered" pitchers (Burleigh Grimes) retired in 1934. The minor leagues had a similar list of "grandfathered" pitchers, but it applied only in the minors so that spitballers who were in the minors in 1920 were effectively trapped there. Frank Shellenback was probably the most notable "grandfathered" minor league pitcher. The spitball does not seem to have been outlawed in the Negro Leagues.
Since Grimes's retirement the spitball has been completely illegal in the majors, but some pitchers have been suspected of throwing it. Notable pitchers who admitted throwing the spitter include Preacher Roe, Don Drysdale, and Gaylord Perry. A number of other pitchers, most notoriously Joe Niekro, were caught throwing the spitter or other defaced ball pitches. Even more have been accused of doing so.
Descriptions of how to throw the spitball vary enough that it seems likely that the term actually refers to at least two different pitches. Some pitchers described a pitch in which saliva was placed on one side of the ball, which was then thrown conventionally. Such pitches would tend to break sideways, with the direction of break controlled by which side of the ball was modified. The same general approach works with a ball that was defaced in any way, either by adding any kind of foreign substance or by scuffing the ball's surface.
In a second approach, the pitcher would grip the ball so that his fingers didn't touch the seams, and use saliva or another slippery substance to lubricate the area where his finger tips touched the ball. He would then squeeze his fingers and thumb together as he threw so that the ball squirted out of his hand rather than rolling off the ends of his fingers. This negated most of the spin on the ball, causing it to drop more than expected, much like a modern splitter. Pitchers who threw this style of spitter often chewed a substance such as slippery elm when pitching in order to improve the lubricating properties of their saliva.
Whichever approach a pitcher took in throwing the spitter, deception was a key part of his arsenal. With most pitches, the pitcher can select his pitch just by changing his grip on the ball. With the spitter, though, he must actually get spit onto his hand or the ball. Even pitchers who were legitimately allowed to throw the spitter needed a way of disguising their intent so that hitters never knew if they were getting the spitball or another pitch. Pitchers who threw the spitball after it had been made illegal had the added complication of needing to throw the pitch in complete secrecy.
 Grandfathered Spitballers
The 17 spitball pitchers designated after the 1920 season were:
- Bill Doak
- Phil Douglas
- Dana Fillingim
- Ray Fisher
- Marv Goodwin
- Burleigh Grimes
- Clarence Mitchell
- Dick Rudolph
- Doc Ayers
- Ray Caldwell
- Stan Coveleski
- Red Faber
- Dutch Leonard
- Jack Quinn
- Allan Russell
- Urban Shocker
- Allen Sothoron
Although Ray Fisher was designated as a legitimate spitballer, he was banned from baseball after the season, so he was unable to take advantage of the designation.