The Rays claimed the submarining right-hander on waivers and then got him from the Orioles in a trade for a player to be named.
"A very interesting acquisition," Tampa Bay manager Joe Maddon said before his surprising team opened a road trip at Seattle. "No hitter says, 'Oh good, we have a sinkerballer coming in.'
"It's a different weapon that we haven't had," he said.
The 33-year-old Bradford is 3-3 with a 2.45 ERA this year. The durable reliever has made 47 appearances and thrown 40 1/3 innings.
Even better for a team expecting to make the playoffs for the first time: He has a 0.00 ERA in 17 postseason games spanning 15 1/3 innings -- no active reliever has pitched more innings in the playoffs without giving up a run.
"This guy's a groundball pitcher. He's durable. He's been very successful in the postseason. And I've heard he's a great guy," Maddon said. "He doesn't give up home runs very often. He gives up singles. Doesn't walk people."
Bradford signed a three-year, $10.5 million contract with the Orioles in November 2006. He has overcome lower back surgery that limited him to 31 games in 2005 and is 34-28 with 11 saves and a 3.31 ERA in 11 seasons.
Tampa Bay began the day with a three-game lead over Boston in the AL East. The Rays expect to have Bradford on Saturday for the third game of this four-game series with the Mariners. Maddon said the team will probably move a pitcher off its roster at that point to make room for Bradford.
That would be yet another move that doesn't involve the return of Rocco Baldelli. The AL's rookie leader in hits in 2003, who has played in just 35 games the last two seasons, has been out all year with chronic muscle fatigue. But he has been cleared medically to play again and has already completed a rehabilitation assignment.
Baldelli is with the team in Seattle and did his usual conditioning workout for his legs in a pool before Thursday's game.
"I've just been on standby the last couple of days," said Baldelli, who with a bushy beard covering prominent cheekbones looks little like the 200-pounder he was before his diagnosis.
When asked if he was anxious to return, Baldelli said, "I was anxious a long time ago."
Maddon said other injuries have kept the team from activating Baldelli. Now, the Rays are waiting for shortstop Jason Bartlett to be fully recovered from getting hit by a pitch on his right index finger Sunday.
"Rocco's on hold until J.B.'s well," Maddon said.