CLEVELAND -- The first thing you hear, after the crack of the bat, is the chorus from the crowd.

It quickly cloaks any clapping. And if you're a certain right fielder from South Korea, it's the most heavenly rhyme of "Boo!" you've ever heard.

"Choooooooo!"

At Progressive Field, that sound has become commonplace. But to the average baseball fan, it might be something more like, "Who?"

Quietly, Shin-Soo Choo had one of the most productive seasons in the Majors last year. He was, in fact, the only American League player to hit .300 with 20 homers and 20 stolen bases.

Outside of Cleveland and Seoul, however, Choo was hardly a household name.

That's changing rapidly in 2010.

"If most of the nation didn't already know about him, they will now," Tribe closer Chris Perez said after watching Choo hit .545 (12-for-22) with four homers and 12 RBIs over the club's past seven games. "He's a legitimate five-tool player."

In a span of four games against the Rangers and White Sox over the weekend, Choo came through with three game-winning hits. His three-run homer in the eighth gave the Tribe a 3-2 win over Texas on Thursday; his eighth-inning single brought home the go-ahead run in a 3-2 win over the Sox on Saturday; and his second-inning grand slam -- the second of his career -- was the difference in a 7-4 win Sunday.

"I want to help the team," Choo said, "and get RBIs."

Mission accomplished there.

This scintillating stretch will die down at some point, of course. But it's no stretch to expect big things from Choo throughout 2010 and in the years to come. The Indians already had one of the more respected young outfielders in the game in Grady Sizemore. Now, they've got two.

"He's got all the tools," Sizemore said of Choo. "He can help you win. Defensively, he can do anything you want. He's improved a lot in the outfield, and he's got a cannon for an arm. He can run the bases, he can hit for average and he can hit for power."

Choo can also hit in the clutch, as evidenced not just by his performance over the past week but also in 2009.

Last year, in the seventh inning or later, with the Indians either leading by a run, tied or with the tying run on base, at-bat or on deck, Choo batted a remarkable .405 with a .542 on-base percentage. Those were, far and away, the top numbers in the league.

In fact, over the past decade, just three players with at least 75 plate appearances -- Barry Bonds (2001, 2004), Albert Pujols (2007) and Aramis Ramirez (2008) -- in close-and-late situations posted an on-base percentage higher than Choo's .542 mark, according to the Elias Sports Bureau.

"If you or I had the same opportunities he has, he would perform better than you or I," Tribe manager Manny Acta said. "When you're that talented, you have a better chance to succeed than the rest of us."

We can safely label the Indians' acquisition of Choo a success. He came to the organization in the 2006 Trade Deadline swap that sent first baseman Ben Broussard to Seattle. Broussard hit .238 for the M's and is now out of baseball, pursuing a music career. Choo, meanwhile, is making joyful noise for the Tribe.

"I have good teammates here, a good team, everything I like," he said. "I feel at home here."

But there are two subplots to Choo's story that have weighed on his mind in recent months.

For one, he turns 28 in July, meaning the window is closing on his timeframe to fulfill his military obligation to his native country. All able-bodied men from South Korea must serve two years by the age of 30.

Choo said he refuses to let that obligation get in the way of his Major League prime. He is hoping to participate in the Asian Games in November, help South Korea win a gold medal in baseball and earn an exemption. But if that scenario doesn't pan out as planned, his only obvious options would be to seek U.S. citizenship, refuse to return to his native land or negotiate some sort of compromise with the government, perhaps serving the military in another capacity after his playing days are finished.

It's a hot-button issue in Korea.

"I try not to think about it," Choo said.

The Indians gave Choo something else to think about this spring, when they approached him and his new agent, Scott Boras, about a contract extension. Choo is under the Tribe's control through his final arbitration year in 2013, and the club attempted to sign him through 2014 with an option for 2015.

Choo and Boras didn't bite. As a result, some Indians fans are already bemoaning Choo's possible departure in a few years, prompting Acta to address their concerns in a recent postgame press conference.

"I think we should appreciate this kid," Acta said, "and enjoy him while he's here."

Choo has given Tribe fans plenty to enjoy, especially in the past week. His success is the product of a life centered on the sport. His high school doubled as a baseball academy, and it was there that he adopted a work ethic that is unmatched in the Tribe clubhouse. He has developed a reputation for being the first one in the batting cage on a daily basis and the last to leave.

"He's a hard worker and a good listener," hitting coach Jon Nunnally said. "He soaks up everything."

Back when Choo was struggling to adapt to facing left-handed pitchers, he sought out advice from Sizemore.

"He would come to me or [Travis] Hafner," Sizemore said. "But halfway through the year last year, we would come to him. I would tell him you need to see guys four, five or six times to know how they're going to attack you, before you can execute a game plan. But he sees a guy one time and hits a double. It makes you say, 'Why can't I do that?'"

So count Sizemore in the chorus of those singing Choo's praises. It's a chorus that seems to grow louder by the day.