But the 24-year-old right-hander struggled on Thursday.
Gray got knocked around for four runs and five hits in one inning in an 8-8 tie between the A's and Arizona Diamondbacks in 10 innings.
He didn't allow a run in his first spring training start after going 5-3 with a 2.67 ERA as a rookie in 2013.
"As good as my changeup was last week, it was hit or miss. It was up and it got hit pretty hard today," Gray said. "It's just something that's going to take a little more work. I felt really, really good so I'm happy with that."
Gray said he needs to get back to trying to get hitters out instead of experimenting with pitches.
"It's just been pitch selection. I have to learn to get guys out with limited stuff," Gray said.
Gray was asked if he was accomplished enough to be able to work on things instead of focusing on stats in spring training.
"Ten (big league) starts, I don't know how accomplished that is," he said.
Arizona starter Trevor Cahill got through three innings, but gave up six runs and eight hits. He struck out four.
Martin Prado continued his hot start to spring training for Arizona with a two-run double, and is 11 for 18 in six games.
The Diamondbacks scored four runs in the first inning and three in the bottom of the eighth to rally for the tie.
Gerardo Parra went 2 for 3 with two RBIs and a stolen base.
Oakland: Gray pitched two shutout innings on March 1, but gave up four straight hits before getting an out on Thursday.
"They hit some fastballs out over the plate, but you're going to have outings like that," A's manager Bob Melvin said. "Not really worried too much about him. If ever there's a time for him to work on a changeup, it's in spring training."
Arizona: Cahill struggled from the start, the former A's pitcher gave up four straight hits in the first inning after getting two outs. Cahill has allowed seven runs and 10 hits in 6 1/3 innings in spring training.
"Got ahead of some guys and couldn't put them away. They jumped on some first-pitches," Cahill said. "Kind of up in the zone a little bit. Other than that, mechanically I felt a little better than the last start."
Oakland: Shortstop Addison Russell might not be ready for the big leagues just yet, but the top prospect showed some offensive potential with a double off veteran closer J.J. Putz and a triple in the ninth inning after which he scored a run to tie the score at 8.
Arizona: Outfielder Tony Campana is trying to win a backup outfield spot, and helped his cause by going 2 for 4 with a stolen base.
Diamondbacks right-hander Bronson Arroyo was at the team facility Thursday after recent treatment for a bulging disk in his back that caused him to miss a spring training start, and is apparently feeling better.
Arroyo, who has pitched three innings in his only start of the spring, was scratched from Tuesday's start for an MRI on his back, which revealed the injury. But manager Kirk Gibson seemed to downplay the diagnosis.
"I think he wanted to throw today (Thursday) but I don't know that was in the cards. Maybe tomorrow," Gibson said before the game. "Just kind of want to make sure we're on solid footing before introducing twisting in his back again. He's had this before. It's kind of resolving itself like it has in the past."
Gibson said Arroyo is still on track to start the regular season in his spot in the rotation.
Oakland: Infielder Alberto Callaspo is dealing with a back problem that could delay his spring training debut at first base. Melvin said a decision will be made Friday.
The A's on Friday will send left-hander Scott Kazmir to the mound for his Oakland spring training debut. It's against Arizona in Phoenix. Kazmir was one of the team's top acquisitions in the offseason. The Diamondbacks will go with left-hander Wade Miley against the A's. Closer candidate Addison Reed gets his chance to pitch after Putz threw an inning on Thursday. The two are competing for the job.