Shields has thrown two scoreless innings in his first two appearances since undergoing surgery on June 16 to repair the patella tendon in his left knee.
The right-hander pitched a scoreless inning against the White Sox last Friday and followed that up by throwing another scoreless inning on Tuesday against the Padres.
"The knee felt good, and that's the most important thing right now," Shields said. "I wasn't able to hit all the spots I wanted to yesterday, but when I needed pitches I was able to make them. I had a little better command with the curveball."
Shields admits he still needs to work on a few things -- he's allowed two walks and two hits in his two appearances but was able to escape jams in both outings.
But Angels manager Mike Scioscia likes what he's seen so far and, with Shields on track to throw every three days, thinks it will only get better.
"The next step is going to be the refinement of his pitches and his command," Scioscia said. "I think the first part has been a success for Scot with his knee and arm being in shape. As he gets through these outings and Spring Training moves on, we'll see some refinement."
Shields is out to prove he can find his form as one of the game's best setup men before his injured knee caused his ERA to spike to 6.62 in 20 appearances last year and he opted for knee surgery.
The 34-year-old is confident he's the pitcher that had a career 2.93 ERA entering last season and not the one that posted a 6.62 ERA last year.
"I know I'm better than that," Shields said. "I know I have a lot more left in me. That wasn't me in there, so I want to bring me back."
And Shields isn't alone in being confident he'll revert to his dominant form.
"I think Scotty is going to be much better than he was last year where it became he wasn't even functional and he needed surgery," Scioscia said. "We certainly know what his talent is when he's healthy, and we're going to need that."
Rhett Bollinger is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.