When Philip Humber stood one pitch away from immortality last Saturday—full count, two outs after he'd retired the first 26 Mariners he'd faced—there was no hesitation about what to throw for the defining pitch of his career. It would be one he had been using for less than a calendar year: the slider.

The choice to complete the 21st perfect game in baseball history was something of a tribute to White Sox pitching coach Don Cooper. Humber, 29, who was drafted third overall by the Mets in 2004, joined Chicago before last season after getting waived twice in a month. He had fewer big league wins (two) than organizations (four). Cooper tweaked the righty's delivery—creating a more downhill angle by reducing the bend in his back leg—and, after three starts, replaced his mediocre cutter with a slider. In his next start Humber took a no-hitter into the seventh at Yankee Stadium. "He whipped out like 25 of them [against the Yankees]," Cooper said on Sunday. "It became his secret weapon."

Beginning with that game, Humber went 8--7 with a 3.67 ERA last year. In his second outing this year he dominated the punchless Mariners, who did not come close to a hit and did not see a three-ball count until the ninth inning. Brendan Ryan, a righthanded hitter, was their last chance. With a full count Humber threw his 19th slider among his 96 pitches. The pitch was far off the plate, but it broke so violently that Ryan started a desperate swing, then stopped. As the ball bounced toward the backstop, umpire Brian Runge ruled a third strike on a swing, prompting Ryan to argue before racing for first. The delay gave catcher A.J. Pierzynski a moment to retrieve the ball and throw to first for the final out.

Humber collapsed on the infield grass, overcome with emotion. His wife, Kristan, was at home, nine months pregnant. The early promise to his career had been validated eight years after his lofty draft status. "He's a guy that's been rejected, neglected and beaten down," Cooper says. "He deserves success because of the price that he paid."

The gem made Cooper, 56, the only active pitching coach with two perfect games on his watch—Mark Buehrle threw one in 2009—and enhanced an already sterling reputation. Since he took over in Chicago in '02, no pitching coach has been better at keeping pitchers healthy and few have revived more stalled careers. Cooper's pitchers have thrown 200 innings in a season 25 times. No other franchise has even 20 such seasons in that span. He also has helped rescue the careers of pitchers such as Jose Contreras, Javier Vazquez, Matt Thornton, Bobby Jenks, Esteban Loaiza, John Danks and Humber. "We do an awful lot of work with pitchers' deliveries," Copper says. "Injuries are not an act of God. Injuries occur because of poor deliveries."

Even in the digital age Cooper retains the old-school manners of a master teacher. "You can overeat, oversleep and overdrink, and I've been accused of all three," Cooper says, "but I don't believe I'll ever be accused of overcoaching."

Continuing a trend from last year, when runs dropped to their lowest level in 19 years, this season has been defined by pitching. Last week alone, as the major league batting average dipped to .247, 49-year-old Rockies lefty Jamie Moyer became the oldest man to win a big league game, A's righty Bartolo Colon threw 38 straight strikes and eight shutout innings, Cliff Lee became the first Phillies pitcher in 55 years to throw 10 shutout innings without a walk, and Humber threw the fourth perfect game in slightly less than three years. "This was certainly not about me," Cooper says. "It's about Phil. This was his moment—after a lot of hard work—when the light shines brightest on a pitcher. It was the perfect storm."


Photograph by ROD


ON-BASELESS CLAIM TO FAME Humber, who before last year had fewer career wins than teams, finally fulfilled some of the promise that made him a top three draft pick in 2004.