Dodgers’ Blake DeWitt is leaving no questions about his hitting

Reporting from Tucson — 

Manager Joe Torre has made it clear that Blake DeWitt’s play at second base will determine whether the converted third baseman makes the Dodgers’ opening day roster.

While uncertainties remain about DeWitt’s ability to play his new position — he has made one error in five starts — he’s making clear that he’s advancing as a hitter.

DeWitt was two for four in the Dodgers’ 7-3 loss to the Arizona Diamondbacks on Saturday and hit his first home run of the spring — a three-run shot to center field in the third inning.

DeWitt is batting .375 this spring and has a .524 on-base percentage.

“You can’t put all of your focus on one aspect of this game,” he said. “You have to try to make their decision as hard as possible.”

A changeup for Chad

Chad Billingsley has spent the past few springs working on developing a changeup, but he was never comfortable enough with the pitch to throw it regularly in the regular season.

He and pitching coach Rick Honeycutt are hoping that the pitch will become part of his arsenal this year.

“That’s the plan,” Honeycutt said.

“It’s a matter of getting the confidence,” Billingsley said. “Adding a changeup can make other pitches more effective.”

Billingsley said he threw his changeup several times during his three shutout innings Saturday.

“They all went well,” he said.

Billingsley pitched his way out of trouble a couple of times, striking out Mark Reynolds with a runner on second in the first inning and getting Augie Ojeda to line into a double play with the bases loaded in the second.

Mattingly manages his son

With the Dodgers not wanting to burden veterans with a two-hour bus ride to Tucson, they took several players from their minor-league camp to face the Diamondbacks.

Among the prospects: Preston Mattingly, the 22-year-old son of manager-for-the-week Don Mattingly.

Preston Mattingly entered the game in the fifth inning as a defensive replacement in left field and was one for two with a single up the middle in the seventh.

“It was a little awkward at first,” he said of sharing a dugout with his father for the first time.

Short hops

Hong-Chih Kuo was scratched from his scheduled start in the final game of the Dodgers’ three-game exhibition series in his native Taiwan because of elbow soreness. Kuo has had four elbow operations. … Third base coach Larry Bowa, who went to an emergency room Friday because of stomach pains, didn’t travel to Tucson but worked out players at the Dodgers’ complex in Phoenix.

dylan.hernandez@latimes.com