Ask sport fans what it takes to play professional baseball and they usually talk about foot speed, arm strength, hitting, and power. Less often do they mention the mental traits, such as focus, concentration, and confidence, that are also required to play baseball at a high level. In keeping with the sport's mania for quantifying everything, baseball players and coaches often put a number on the mental dimension as a way of stressing its importance. "Succeeding in pro ball is 90 percent mental. It's big," said Diamondbacks infielder Andy Fox. "Baseball is 80 percent mental," said one manager, "you have got to make players believe in themselves to perform well." Or, in the words of former Kansas City outfielder Jim Wohlford, "Baseball is 90 percent mental half the time."  Actually, Wohlford's Yogi-ism is probably the most accurate of the three in that some aspects of baseball are more mentally demanding than others.
While these numbers are just figures of speech, they do reflect the great stock baseball people put in the psychological dimensions of playing pro ball. Much evidence suggests they are right. For example, how else can we account for the large number of Minor League players who have all the physical "tools" to play in the Major Leagues but never make it, while less-talented players do. More telling still, 35 percent of all first round draft picks--the most talented and heavily scouted players in the annual draft--never make it to the Major Leagues. "The difference between a good year and a bad year is mostly in the head," said Birmingham Barons' manager Tony Franklin, who attributed the difference in his .280 batting average one year and .230 average the next solely to a decline in his ability to concentrate. Recognizing the importance of a player's mental makeup, most baseball organizations now ask prospects to take a psychological test, such as the Athletic Motivation Inventory. So far the tests have not bee n very good predictors of later success, but they can point out character weaknesses or psychological vulnerabilities that coaches can take into account.
This paper examines some of the mental dimensions of playing pro ball, from what players do mentally to prepare for the game to how they deal with variabilities in their performance. While there are many dozens of excellent books on the game itself and the strategies used in playing it, Little attention has been given to the mental side. It is an aspect of pro ball about which we still know very little.
The data come from more than one hundred tape-recorded interviews with Minor and Major League players, conducted as part of a larger investigation into the life and culture of professional baseball. The research also involved observation and informal interviewing, some of it conducted while living and traveling with the Minor League Jamestown Expos and the Birmingham Barons; and to a limited degree the paper is also informed by my own experiences as a Minor League player in the 1960s.
The physical preparations a ballplayer engages in before the game--running, throwing, stretching, batting practice, and fielding ground and fly balls--are well known to those fans who arrive at the ballpark early. What is not visible are preparations of the mind. Starting pitchers often begin preparing for their next start the day after their last outing. "The next morning in the shower you start thinking about your next opponent, who their key hitters are and how you're going to pitch to them" said the Giants' Russ Ortiz. Many pitchers will follow their next opponent in the box scores and on ESPN's nightly highlights, and if the games are broadcast they'll try to watch. "I go over their stats mainly to look at home runs so I know who the major power hitters are and I look at stolen bases so know who can run," said the White Sox's Brian Keyser. "It's a gradual progression of concentration up to the day I pitch." Preparations are particularly involved on the day they pitch. …