The 29-year-old Thornton struggled last season with the Mariners, going 0-4 with a 5.21 ERA in 55 games. He has a 4.82 ERA in 74 career relief appearances with Seattle.
"It's difficult to give up on a guy who throws 94 mph,''
Mariners manager Mike Hargrove said Monday. "Things didn't work
out for Matt here, but hopefully for him everything will come
together for him in a different environment.''
Thornton's problems continued this spring. He allowed 11 runs and 18 hits in seven innings of exhibition play for a 14.14 ERA. In his last outing against San Francisco, he was knocked around for five runs in one inning.
"[Seattle] had high expectations for me, and I guess I didn't live up to those expectations," Thornton said in the Mariners' clubhouse.
The 27-year-old Borchard was at Triple-A Charlotte for most of 2005 and finished second in the International League with 29 home runs. He spent the last month of the season with the White Sox, playing in seven games and going 5-for-12.
The switch-hitter appeared in 102 career games with Chicago, hitting .191 with 12 homers and 30 RBI over four seasons.
This spring, Borchard was batting .324 with two homers and seven RBI in 14 games. He is expected to challenge Mike Morse in the final days of camp for a spot on Seattle's bench.
"At this point, I'm not sure if we'll carry four or five outfielders, and we'll wait and see what happens," Hargrove said. "The plus for [Borchard] is that he plays all three outfield positions and is a switch-hitter."
Thornton said he was excited to join the World Series champions. Neal Cotts is the most experienced left-hander in Chicago's bullpen.
"Being traded is a new experience for me. I don't know how to react to it," Thornton said. "I've heard some good things about Ozzie Guillen, and I'm looking forward to playing for him."
By trading Thornton, Seattle loses one of its few left-handed pitching options. Aside from starters Jarrod Washburn and Jamie Moyer, closer Eddie Guardado is the only left-hander assured of making the roster.
Hargrove said he is prepared to go without any lefties in the bullpen aside from Guardado.