It was only Darvish's eighth start of the season because of time missed while he recovered from Tommy John elbow reconstruction surgery and another five weeks because of discomfort in his right shoulder.
Darvish still compared his work to 2013, when he finished second in the American League Cy Young Award voting.
"I feel like I'm pitching better than 2013," he said.
Darvish was in complete control on Sunday. He allowed five hits, struck out eight and did not walk a batter. He threw 93 pitches before turning over a 3-0 lead to the bullpen in the bottom of the eighth.
Darvish said everything worked because he was able to rely mainly on his fastball and sinker and let the other pitches work off those two.
"I felt like they played a big part of the success today, throwing a lot of four-seam fastballs inside to the lefties," Darvish said. "To the righties, I threw a lot of sinkers in, and it worked well. I think that played a big part in the success I had. Just being aggressive with the four-seam and sinker, and that was good enough. I didn't have to throw many other pitches."
He also seemed to click with new catcher Jonathan Lucroy, who was catching him for the second time since being acquired from the Brewers.
"I feel like we're on the same page even better than the last time we worked together," Darvish said.
Darvish did not get the win because the Astros rallied late against the Rangers' bullpen to force extra innings. But that seemed inconsequential.
"Big step forward for him, because of the confidence and the feel for his pitches," Banister said.
T.R. Sullivan has covered the Rangers since 1989, and for MLB.com since 2006. Follow him on Twitter @Sullivan_Ranger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.