In Florida and Arizona, 30 hopeful Major League baseball teams currently are preparing for another marathon season: 162 games of drama and glory that will culminate in the World Series. There will be scores of hits and runs and errors, walk-offs and brushbacks, double-switches and controversial second-base slides. But what makes baseball so great and timeless is the simplicity at its core. In Bull Durham, Trey Wilson famously huffed at his underachieving crew, “This is a simple game. You throw the ball. You hit the ball. You catch the ball.”

But even Wilson (and writer/director Ron Shelton) might have been overcomplicating things. Because baseball, at its heart, is just “a primal battle between a man with a stick and man with a rock.” That’s a line from the trailer for Fastball, the new documentary narrated by Kevin Costner that takes a closer look at the flamethrowers who challenge hitters with 100 m.p.h. heat and the sluggers who have milliseconds to decide to swing or duck.

In baseball, there’s a term to describe the stuff of a pitcher who’s untouchable: electric. When a pitcher who can crank it up to the high-90s has his A-game, base hits are accidents that almost demand an apology. The pitches practically hum and the sound of it popping the catcher’s mitt can turn heads in the upper deck. “You can definitely hear a fastball,” says Derek Jeter. “It sounds like trouble, is what it sounds like.”

In an exclusive clip from the documentary, which opens in theaters and on-demand on March 25 (two days after special fan screenings), scouts marvel at the majesty of the fastball that speaks truth to the radar guns. A 90-plus fastball is the sport’s Holy Grail, worth millions to any kid blessed with a thunderbolt arm. (Just ask Ebby Calvin “Nuke” LaLoosh, who loved to announce his presence with authority.)

Fastball is produced by Legendary executive Thomas Tull, who made the Jackie Robinson movie, 42. Partnering with Major League Baseball, director Jonathan Hock’s film takes you inside the game in a way most fans have never experienced before. It will undoubtedly give a newfound appreciation for the near-superhuman ability to throw a ball, and the courage and skill it takes to turn a 98 m.p.h. heater around and drill it into the upper deck.