TUCSON, Ariz. -- After battling through arm injuries during Spring Training in 2007 and '09, Angels right-hander Jered Weaver decided to alter his throwing program this offseason.

Weaver took just one month off before beginning his throwing program on Jan. 1 with the plan to build up his arm strength in time for the start of Spring Training.

So far, it's paid off. Weaver has experienced no arm troubles and it showed on Thursday against the D-backs when he allowed just one run over three innings at Tucson Electric Park.

"You just try to do something different because sometimes I come into camp with some tendinitis in my shoulder, so I activated my arm sooner this offseason," Weaver said. "So I just felt better coming into camp this offseason. But you have to adjust and see how your body adapts from the season before."

Angels manager Mike Scioscia has noticed the difference and feels like Weaver has it figured out as he enters his fifth big league season.

"The last couple springs he's found the balance of where he needs to be and what he needs to do," Scioscia said. "After his first year there was some learning for where he needed to be, but he came back and he's found that balance. Every offseason you have to kind of see how your body feels and what kind of work you need to get in, so he's done a good job getting ready the last few years."

Weaver's outing on Thursday was much better than his previous start on Sunday, when he allowed two runs on three hits over 1 2/3 innings against the A's.

But Weaver attributed that to the fact that he was simply working on a few things in his last start and that this was the first time he really began to mix in his offspeed pitches.

"I threw more offspeed pitches than my last outing when I mostly had a fastball-changeup for the most part," Weaver said. "You're throwing your fastball more than you would, but now I'm throwing some offspeed stuff in fastball counts and getting a feel for that."

It's all part of the process for Weaver as he tries to become the ace of the staff after the departure of former ace John Lackey who departed to Boston via free agency.

Weaver is the top candidate to be the Angels' Opening Day starter, but he knows that decision is ultimately not in his hands.

"It definitely has to be earned," Weaver said. "It's fun to look down the road but they haven't quite the made the decision yet. So I'm going to go out there and throw the ball the way I know how and let everything fall in place."

So while Weaver is healthy and aiming for a spot atop the rotation, Angels reliever Scot Shields is aiming to be healthy this season as well. He is expected to make his Spring Training debut on Friday against the White Sox at Tempe Diablo Stadium.

Shields hasn't pitched in a game since May 16, 2009, also against the White Sox, after undergoing surgery on June 16 to repair the patella tendon in his left knee.

Scioscia called Shields "game-ready" and also had encouraging news about fellow relievers Kevin Jepsen and Fernando Rodney, both of whom have yet to make their Spring Training debuts with Rodney battling sore shins and Jepsen resting his arm after throwing 54 2/3 innings in his first full big league season last year.

"[Rodney] is very close," Scioscia said. "He feels really good. He has a simulated game in the next couple days and we'll evaluate him and see how [pitching coach Mike] Butcher feels. And Jepsen is doing great and will likely throw a simulated game when Rodney does."