Seattle's Bret Boone Matures As An All-Around Performer.

Mariners second baseman has emerged as one of the game's best defensive players while improving his productivity with the bat

BRET BOONE SWAGGERED INTO Seattle's clubhouse in 1993 with a personality as strong as his swing.

He was a 24-year-old whose 12 home runs in half a season set a franchise record for second basemen.

"He was really cocky and a very confident kid," Jay Buhner said. "He knew he could back it up."

Boone, now a 32-year-old veteran, has become bigger for his second stint in Seattle. He added 15 pounds of muscle in the offseason, his always-big forearms ballooning toward Popeye proportions as he fills a bigger role in the middle of the Mariner lineup. As the No. 5 hitter, he drove in 80 runs in his first 80 games through July 1, ranking first in the American League.

But Boone is a bigger person, too, his confidence tempered by nine seasons in the major leagues, though not completely tamed.

"I've just grown up a lot," he said. "It's a humbling game, and you never take it for granted. I realize how tough it is, so it's something that I don't take for granted. I think when I was younger I did because I didn't have much adversity, but sometimes I see a lot of young guys who are like that.