But in the fifth, Richards hit a speed bump.
After coaxing a groundball to start the inning, Richards surrendered consecutive singles to Yonder Alonso and Marcus Semien. He retired the next batter but then threw a 94-mph fastball to Matt Joyce that triggered the concern of catcher Martin Maldonado, who signaled for the team trainer to come out to the mound. Richards subsequently departed the game with a right biceps cramp, dampening the Halos' 5-0 win over the A's at the Coliseum.
The club announced that Richards' removal was precautionary, and he said afterward that he wasn't concerned about the issue, which was called a cramping of his right biceps.
"My bicep was just kind of cramping a little bit," Richards said. "Nothing serious. My arm feels good. I felt good tonight. Elbow feels fine. Shoulder feels fine. It was kind of a long inning and I kind of stiffened up a bit, but nothing to be worried about."
Manager Mike Scioscia said Richards will be evaluated by team doctors when the Angels return to Southern California following their series finale against the A's Thursday, but as of now, there are no plans for the 28-year-old right-hander to undergo an MRI.
"We're going to take it one step at a time," Scioscia said. "As of right now, hopefully he'll make his next start. We're not going to take any chances with any pitcher that's feeling something like that, let alone a guy that went through what he went through last year."
While Richards' premature exit was a little disconcerting, the Angels were encouraged by what they saw before he left the game. Richards allowed just three hits, walking one and striking out four, in the 76-pitch effort.
"After the first inning, I felt like I settled in a little bit," Richards said. "But I did today what I've been trying to do, which is fill up the zone, kind of go right after guys and make them hit my pitch."
Much of the Angels' success in 2017 figures to hinge on the health of their starting rotation, which is anchored by Richards.
Richards made only six starts in 2016 before he was diagnosed with a torn UCL. The loss of Richards and left-hander Andrew Heaney, who also suffered a season-ending elbow ligament tear, crippled the Halos' rotation and derailed their season. Richards avoided Tommy John surgery by receiving an injection of stem cells in his damaged elbow, and his return was a boon to the Angels, who need his presence at the top of their rotation.
For now, the Angels will continue to tread carefully with their ace, though Richards said he's confident he'll be able to move forward without any further setbacks.
"Everything kind of moves on as planned," Richards said.