Jennings, who arrived at Phoenix Municipal Stadium on Sunday after catching an early flight out of Dallas, will play catch immediately and then throw a bullpen session Monday. Meanwhile, Tomko will join Minor League camp this week to continue rehabilitation of last year's arm injury that sidelined him following six impressive starts -- which resulted in a 4-1 record and 2.95 ERA -- with the A's. If all goes well with his rehab schedule, Tomko should be good to go in May.
The 31-year-old Jennings owns a 62-74 lifetime record and 4.95 ERA in 225 games, including 180 starts, in nine big league seasons. He was the Rockies' first-round pick in the 1999 First-Year Player Draft before going on to earn 2002 National League Rookie of the Year honors with Colorado. In six seasons with the Rockies, he compiled a 58-56 record and 4.74 ERA, making him the franchise's winningest pitcher.
Jennings was traded following the 2006 season to Houston, where he started 18 games, before signing as a free agent with Texas in January 2008. He appeared in just six games with the Rangers, posting a 0-5 record and 8.56 ERA, and was then moved to the bullpen and released in late August.
"I felt like I threw well last year, and this is the healthiest I've felt since '05," said Jennings, who experienced elbow problems the past couple seasons. "I was just waiting on an opportunity to pitch, and I feel like I can fill multiple roles here."
Jennings said he came close to a deal with the Giants, and also had interest from the Cardinals and Mets. In the end, though, he said he liked all Oakland had to offer -- including a chance to reminisce with Ben Sheets, whom he hit a home run against in college.
"I'm happy with this opportunity," he said. "This seems like a young, energetic team. I enjoyed watching them last year, and hopefully I'll be a part of it this year."
Manager Bob Geren said he likes the possibility of using the newly acquired Jennings in a multitude of roles, including as a starter, or in middle and long relief.
"I've heard he's 100 percent healthy, so we'll treat him as anyone else," the A's skipper said. "He not only adds depth, but experienced depth."
Meanwhile, Tomko is no stranger to the A's, as he initially signed a Minor League contract with Oakland on Aug. 5 of last year after being released by the Yankees. Before ending his season with an irritated nerve in his right arm, the 36-year-old righty earned his 100th career victory with a five-hit shutout against Texas on Sept. 15.
Tomko's career line includes a 100-102 mark and 4.65 ERA in 389 games (266 starts) over 13 Major League seasons, during which he's pitched for nine teams.
In their Major League careers, Jennings and Tomko have combined for 162 victories and 614 appearances.
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.