Moyer, who hails from nearby Sellersville, Pa., and attended St. Joseph's University in Philadelphia, had to approve the move as a 10-year veteran with five years on the Mariners. The decision came down to Seattle's recent nine-game losing streak and its fading playoff hopes.
"He wanted to pitch for a club that had an opportunity to go to the playoffs," Gillick said of Moyer, who serves as his own agent.
Moyer, who had the lowest run support in the American League, is 6-12 this season with a 4.39 ERA, but the Mariners' all-time wins leader is 211-164 over his 20-year career. The 43-year-old, who will turn 44 in November, is making $5.5 million and will be a free agent at the end of the season. Moyer and the Phillies worked out a mutual option for 2007.
The lefty, whose pitches come in two speeds -- slow and slower -- will join the team in Chicago. After starting for Seattle on Thursday, he would be ready to replace the struggling Scott Mathieson in the rotation on Tuesday should manager Charlie Manuel and pitching coach Rich Dubee choose to go that route.
The deal, which assistant general manager Ruben Amaro Jr. said took three days to work out, excited the Phillies' front office.
"He not only brings experience, but this guy can win," Gillick said. "He's kind of a guy who's flown under the radar for a long time.
"He's throwing under hitting speed. That's what he does."
Both Phillies prospects in the deal were at the Class A level. Baldwin was 8-8 with a 4.04 ERA for Clearwater, while Barb was 6-2 with a 2.23 ERA in Lakewood. Barb came in to relieve Carlos Carrasco on Sunday in the duo's joint no-hitter.
Zachary Levine is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.