PEORIA — Sonny Gray last season was the kind of pitcher to respond to an occasion (his ALDS duels with Justin Verlander the most obvious examples). It's a little different when the occasion is a spring training start in which he's working more on developing pitches than getting outs, as was the case in his last outing March 6 against the Diamondbacks.

Gray allowed four runs on five hits in an inning in that start. He also didn't throw either his sinker or curveball, while trying to bring along a changeup as another offspeed option. Tuesday, in his subsequent start against the San Diego Padres, Gray said he threw all his pitches and treated the outing more like a regular-season game. The result: four innings, no runs, one hit and two strikeouts.

"It was a completely different mindset," Gray said. "And that's really big for me, if I'm on the mound thinking, 'Let's go after this guy, let's get this guy,' rather than working on stuff and feeling my way around."

Another factor: Last week against Arizona was Gray's first time throwing to catcher John Jaso — ever.

Tuesday, Gray said, "We were really on the same page, which was awesome. He did a great job trying to learn my strengths and my weaknesses."

Throwing the curveball and sinker, Gray said, allowed him to get a lot of early contact — one reason he was able to complete four innings on 45 pitches. Most of his outs came on the ground, another good sign.

"Really good," manager Bob Melvin said. "He's a guy that grinds on everything and today was pretty serious down in the bullpen, which you like to see, too. He had everything working today."

Gray is one of the pitchers Melvin has referred to opaquely as candidates to start for the A's on Opening Day. "I don't know," Gray said. "It would be cool."

A semi-familiar face was back with the A's on Tuesday as Hiro Nakajima joined the travel roster for their 6-5 loss to the Padres. Nakajima has been in minor-league camp this spring, but with top shortstop prospect Addison Russell expected to miss a week after straining his right hamstring Monday, Melvin said Nakajima could get into some games.

Melvin said this morning that first baseman Daric Barton (hamstring) is several days away from playing in games again. Catcher Derek Norris (back) could be in the lineup today after being out since Friday. Outfielder Craig Gentry (back), who has yet to make his spring debut, ran and hit off a tee Monday.

Reliever Eric O'Flaherty took a significant step in his return from Tommy John surgery Tuesday, throwing his first bullpen session at the A's facility in Phoenix. The A's are still targeting midseason for O'Flaherty being available to join the bullpen.

Set-up man Ryan Cook (shoulder) also threw a bullpen and "threw the ball really well again," Melvin said. Cook has not pitched in a game yet says he'll be ready for Opening Day.

Coco Crisp, who came in with one single in 13 Cactus League at-bats, doubled in his first two at-bats. The first double started a three-run first inning for the A's, as Jaso followed with a double and Jed Lowrie hit his first home run of the spring.