In baseball, the pitcher is the player who throws ("pitches") the baseball from the pitcher's mound toward the catcher to begin each play, with the goal of retiring a batter, who attempts to either make contact with the pitched ball or draw a walk.
In most cases, the objective of the pitcher is to deliver the pitch to the catcher without allowing the batter to hit the ball with the bat.
A successful pitch is delivered in such a way that the batter either allows the pitch to pass through the strike zone, swings the bat at the ball and misses it, or hits the ball poorly (resulting in a pop fly or ground out).
If the batter successfully checks the swing and the pitch is out of the strike zone, it is called a ball.
A pitcher's particular style, time taken between pitches, and skill heavily influence the dynamics of the game and can often determine the victor.
Other common types of pitches are the curveball, slider, changeup, cutter, sinker, screwball, forkball, split-fingered fastball, slurve, knuckleball, and vulcan.
[4] These generally are intended to have unusual movement or to deceive the batter as to the rotation or velocity of the ball, making it more difficult to hit.
Some pitchers release pitches from different arm angles, making it harder for the batter to pick up the ball's flight.
The most common style is a three-quarters delivery in which the pitcher's arm snaps downward with the ball's release.
A full game usually involves 120–170 pitches thrown by each team, and most pitchers begin to tire before they reach this point.
The act of throwing a baseball at high speed is very unnatural to the body and somewhat damaging to human muscles; thus pitchers are very susceptible to injuries, soreness, and general pain.
Barring injury or exceptional circumstances, the ace is usually the pitcher that starts on Opening Day.
Aces are also preferred to start crucial games late in the season and in the playoffs; sometimes they are asked to pitch on shorter rest if the team feels he would be more effective than the 4th or 5th starter.
Differences in rotation setup could also have tactical considerations as well, such as alternating right- or left-handed pitchers, in order to throw off the other team's hitting game-to-game in a series.
This involves the reliever starting to throw practice balls to a coach in the bullpen so as to be ready to come in and pitch whenever the manager wishes to pull the current pitcher.
More recently, teams began experimenting with an opener, a relief pitcher who starts a game but only pitches at least the first inning.
(For instance, in a 1993 game, Jose Canseco suffered a season ending arm injury after pitching 2 innings.)
Cliff Pennington of the Toronto Blue Jays, who pitched 1⁄3 of an inning in game 4 of the 2015 American League Championship Series en route to a 14–2 loss, was the only documented position player to pitch during the postseason, until Austin Romine of the New York Yankees pitched the ninth inning of Game 3 in a 16–1 loss against the Boston Red Sox in the 2018 American League Division Series.
The only regulation game in which both pitchers of record were position players occurred on May 6, 2012, when the Baltimore Orioles' designated hitter Chris Davis was the winner in a 16-inning game against Boston while Red Sox outfielder Darnell McDonald took the loss.
Most major league pitchers throw at speeds of 70 to 100 mph (110 to 160 km/h), putting high amounts of stress on the pitching arm.
As such, the biomechanics of pitching are closely studied and taught by coaches at all levels and are an important field in sports medicine.
Glenn Fleisig, a biomechanist who specializes in the analysis of baseball movements, says that pitching is "the most violent human motion ever measured.
[9][10][11] Some players begin intense mechanical training at a young age, a practice that has been criticized by many coaches and doctors, with some citing an increase in Tommy John surgeries in recent years.
[14] Jobes are exercises that have been developed to isolate, strengthen and stabilize the rotator cuff muscles.
In addition to the Jobes exercises, many pitching coaches are creating lifting routines that are specialized for pitchers.
Handling the bag applies a small layer of the rosin to the pitcher's fingers in order to increase his grip on the ball.
[15] San Diego Padres relief pitcher, Alex Torres was the first player in MLB to wear the protective cap.
[16] One style of helmet is worn on top of the ballcap to provide protection to the forehead and sides.