Philadelphia - The San Diego Padres picked ninth in the 2000 draft, so they knew they would have no chance to take the local first baseman with the uncommonly mature approach at the plate. Even so, a young Padres executive who was just learning to scout decided to watch him play. Thus began the relationship between Adrian Gonzalez and Theo Epstein.

Epstein, then working in the Padres' baseball operations department, wanted to see all the top players in the area, to refine his eye for talent. He remembers Gonzalez for the natural way he drove balls to the opposite field, letting pitches travel a split-second longer before lashing line drives off the barrel of his bat. Gonzalez had smooth hands in the field and a frame that suggested a future slugger.

The Florida Marlins selected Gonzalez first, and after two trades he landed with the Padres in 2006. By then, Epstein had become the general manager of the Boston Red Sox, and Gonzalez was such a star that his talent was obvious to all.

''Look, my 3 1/2-year-old son could scout Adrian Gonzalez," Epstein said last week, in the visiting dugout at Citizens Bank Park. "It doesn't take anything special to do that. It was pretty obvious to everybody that he'd be a good fit at Fenway Park and in our lineup. And he was such a good fit that he made us be aggressive."

Epstein traded for Gonzalez in December, sending three prospects and utility man Eric Patterson to the Padres, who could not afford his rising salary. Gonzalez signed a seven-year, $154 million contract extension and has been an immediate sensation.

Through last Wednesday, Gonzalez was atop the majors in batting average (.352, tied with Jose Reyes), runs batted in (71) and total bases (194), with 16 home runs and his usual standout defense. On Tuesday he played right field, so the Red Sox could use David Ortiz at first base in a National League park.

Terry Francona, the Red Sox manager, said he gave no consideration to resting Gonzalez, who had played the outfield just one previous time. Gonzalez, who after Thursday's 5-2 victory over the Phillies has played in each of Boston's 80 games this season, offered to take Sunday off for Ortiz.

''I told him no," Francona said. "He's the best hitter in the game."

The claim is not far-fetched. Last season, only one National League position player, Albert Pujols, outranked Gonzalez in wins above replacement (WAR), according to Baseball-Reference.com. This season, through Tuesday, only Jose Bautista of Toronto ranked better in the American League.

''There's not anybody I would trade him for," said Dave Magadan, the Red Sox hitting coach. "He's as good as it gets. He goes into every game with a pretty good plan, he really bears down with runners in scoring position, and if he doesn't get a hit, he usually hits the ball hard somewhere. He's been a pleasure to watch. He's come as advertised."

Magadan had an advance preview. As the Padres hitting coach in 2006, he was sold on Gonzalez from the first time he threw batting practice to him in spring training. Gonzalez sprayed liners to all fields and showed the same skill Epstein had observed in high school: Everything, it seemed, came screaming off the barrel of the bat.

Magadan, the former New York Met, had little power when he played. But, like Gonzalez, his natural swing produced hits to the opposite field while confounding his coaches, who believed hitters should pull and wait until two strikes to use the entire field. An opposite-field swing, Magadan said, was thought to equate to a slow bat.

Gonzalez's brother Edgar, a former Padres teammate, had a more traditional gap-to-gap swing when the boys were growing up. Adrian's swing was always geared toward left field.

''I never learned how to pull the ball until - I don't know - Triple-A," Gonzalez said. "People would try to change, but I would try to become more of a pull hitter and go into a slump. Eventually it would be like, 'That's not me.'"

His approach could be frustrating at San Diego's Petco Park, with its deep dimensions and thick marine air. Fly balls to left field tend to stay up and die in fielders' gloves. Gonzalez, a .291 career hitter, hit only .267 there, compared to .380 at Fenway Park, with its inviting left field wall.

Phillies manager Charlie Manuel, who has mentored standout opposite-field hitters like Jim Thome, Manny Ramirez and Ryan Howard, said the new environment was bound to make Gonzalez more dangerous. The way he hits, Manuel said, is ideal.

''From a fundamental standpoint, from a mechanics standpoint, if you see the ball and you have a nice, smooth, easy stride and good swing, that's what makes good hitters," Manuel said. "Usually a real good hitter, he doesn't have a whole lot of weaknesses."

Gonzalez said he has not changed anything about his approach this season. The only difference, he said, is that he is getting more hits and walking less often. By leaving Petco for Fenway, and using his natural swing, he has produced the results Epstein expected.

''He's an intelligent guy, so he's really aware," Epstein said. "You can throw a lot of different things at him, and in the end, he still knows himself extremely well when he steps in the batters' box. He slows the game down to his speed, and he goes out and executes."