Sweeney, acquired from the Seattle Mariners in a trade, will join the club Thursday in Florida. He will wear No. 5, the first Phillie to do so since Pat Burrell left after the 2008 season. The corresponding move on the 25-man roster will be decided Thursday.
The Phillies put in a waiver claim on Sweeney. Seattle pulled him back and the two clubs worked out a deal for either a player to be named or cash considerations.
Whatever the Phillies surrender, it won't be much. That makes it a low-risk move, much like post-July 31 moves the Phillies made for Jeff Conine, Jose Hernandez, Jamie Moyer, Scott Eyre and Tadahito Iguchi in recent years.
"Obviously, he's not as productive as he used to be," Amaro said of Sweeney. "But we still think in the limited playing time he might have that he has a chance to win some games for us."
Sweeney, in his 16th season, was hitting .263 with an .802 OPS in 30 games for Seattle. He has been on the disabled list since June 25 with back spasms, but the Phillies said Sweeney is ready to play immediately after reviewing his medical records. Sweeney played 12 games in a rehab stint for triple-A Tacoma.
In his final rehab game Tuesday, he hit two home runs and played first base. Phillies superscout Charley Kerfeld was in attendance. But the 37-year-old Sweeney has started just 25 games at first base in the majors since the end of the 2005 season. The last time he played first base full-time was in 2002.
Still, the Phillies view him as an upgrade to the Ross Gload-Cody Ransom platoon now in place.
"I don't know if we had to do anything," Amaro said. "But I think this helps because it gives us a guy who is a bona fide major-league hitter and has had a ton of success."