Mind may be MVP of the diamond.

• Position: Sports Psychology - Most valuable player

"Hope springs eternal" in the heart of every baseball fan and nothing trumps the feeling of emerging from the turnstiles to absorb the comforting vision of lush, green grass, a meticulously manicured infield, and crisp, white foul lines. The starting lineup, read with pent-up energy over the public address system, and the tempting aroma of ballpark fare are traditions of the game captured in two momentous words: "Play ball!" Yet, what makes it possible to play baseball may look more like psychology than the national pastime.

"Yogi Berra said baseball is 90% mental; the other half is physical. While his math is questionable, he's right. Baseball is an incredibly mental game. The physics of baseball impose physical limitations on the game, and the players' biology imposes physiological limitations; psychology mediates between the two," explains Mike Stadler, associate professor of psychology and associate director of the honors college at the University of Missouri, Columbia, as well as the author of The Psychology of Baseball: Inside the Mental Game of the Major League Player.

Stadler notes that, when considering the physics of baseball, it should be impossible, for...