As the A's went through the paces of opening night batting practice, a solitary voice cried out from the stands."Hey," the male fan yelled out to the guys in green and gold, "who are you guys?"Some three hours later, Yoenis Cespedes gave not only the paying customer, but the entire sold-out crowd at the Oakland Coliseum an answer. A thundering, 462-foot, shake-Mt. Davis-to-its-bloody-core retort.Cespedes, the Cuban defector whose rights were surprisingly won by the notoriously thrifty A's, announced his presence with authority, to borrow a line from the seminal baseball classic "Bull Durham." His fourth-inning home run, a two-out, two-run blast on a 2-and-1, 84-mph fastball down the pipe that ricocheted off the facade of the second deck in left-center field, was a thing of monstrous wonderand beauty.It echoed Miguel Tejada at the height of his powers. Bo Jackson in the 1989 All-Star Game. Frank Thomas in his epic 2006 season with the A's."I've hit some farther in Cuba," a chagrined Cespedes said in Spanish.Indeed, it was the hardest-sounding hit ball by an A's batter since The Big Hurt made a run at the MVP award six years ago. Yes, "sounding."Because even when Cespedes took batting practice, you could tell when it was him in the cage. Simply by the sound of the ball coming off his bat. The same way you could tell it was Thomas taking his hacks."You don't see too many here at night that go that far," offered A's manager Bob Melvin. "He'll hit them farther than that."Granted, Thomas should be in Cooperstown in a few years while Cespedes was playing his third -- ever -- game in the major leagues. So the comparison is oh-so unfair. But this is what happens when a moribund franchise in desperate need of a marquee player that makes you stop what you're doing every time he comes to the plate lands such a hitter.The way Tejada did. And Jackson. And yes, Thomas.Even when the 5-foot-10, 210-pounder -- he looks much larger -- is striking out. As he did in the sixth inning. Swinging. And in the eighth. Looking.These A's, though, seem to get stage fright under the bright lights of opening night. In falling to Seattle, 7-3, the A's lost their eighth straight Coliseum opener.And you expected Cespedes to have butterfiies?Nerves are what Cespedes experienced as he planned his defection last summer to the Dominican Republic. When the five-tool player left behind everything and anything he has ever known. When he put pen to paper to sign that four-year, 36-million contract with the A's to realize a dream of playing in Las Grandes Ligas.In eight seasons playing for Granma in Cuba's Serie Nacional, Cespedes hit 177 home runs. And in his final season, he batted .333 with 30 homers and 99 RBI in 90 games.So yeah, he could rake. But the Mariners also showed respect for his arm, the speedy Chone Figgins not daring test him by tagging from third base on a medium-range fly ball in the third inning."He looks to be a true center fielder," Melvin said.But in getting full extension on his home run, the 26-year-old rookie pulled the most veteran of moves in admiring his shot at the plate before embarking on his fanciful trip around the bases.In Cuba, where the games have more showmanship than stateside, Cespedes would have watched the flight of his ball longer, and with more aplomb.Instead"What are you doing?" Cespedes asked himself, before sheepishly realizing where he was and exiting the box.Eight days earlier, on another continent, Cespedes homered off Seattle's Shawn Kelly in the Tokyo Dome. So when his 462-foot bomb off Jason Vargas cleared the fence, Cespedes become only the second A's batter since 1918 to homer twice in his first three games.The other? His Cuban countryman Bert Campaneris, who did it in 1964for the Kansas City Athletics.Cespedes raised his brow in wonderment."I'm very content to hear that," he said. "He was not only one of the best players with the A's, but one of the best to come from Cuba. So to be in his company, that makes me very happy."Who are these guys?Cespedes more than introduced himself.