"It's just keeping me from being able to rotate," said Jepsen, who said he hopes to play catch on Wednesday. "So when I'm pitching, I can't get there fully and get the ball to the zone."
Jepsen said his rehab process entails getting soft-tissue massages on his back while also using heating pads. He said it should take about five days before he feels ready to throw off a mound, but that it doesn't make his first trip to the DL any easier.
"It's definitely frustrating," said Jepsen, who made his big league debut last year after pitching out of the bullpen for Team USA in the Olympics. "You want to get out there and play and pitch the way you know you can."
Wood, 24, was called up after batting .346 with four home runs and eight RBIs in seven games with the Bees.
Wood has established himself as a great Minor League hitter but has combined to hit just .191 in 183 big league at-bats between 2007 and 2008.
But after being called up on Aug. 28 of last season, he fared much better, batting .256 with four home runs and 11 RBIs in 26 games.
"Last year was good for me to get those consistent at-bats," Wood said. "I felt I really helped the team, so I feel it's a confidence thing."
Wood will serve in a reserve role with the Angels, according to manager Mike Scioscia, and if he doesn't get enough at-bats he might get sent back to the Minors.
"Right now, he's going to be a reserve player for us," Scioscia said.
"We're confident he can go out there and help us, but he won't be up here sitting for two weeks or three weeks without playing. If there's no role for him, then we'll have to reevaluate it."
Wood, though, will be playing with a heavy heart with the Angels as he lost his teammate, Nick Adenhart, and one of his best friends, Henry Pearson, in a hit-and-run accident that killed the two men as well as Courtney Stewart on April 9.
Wood missed three games in the Minors to attend the funeral of Pearson, whom he met through a friend while Pearson was attending Arizona State.
"Losing Nick and him on the same day, a great teammate and a great friend, it was a tough one," Wood said. "I think we're just trying to move on and keep our smiles and remember them in a happy way."