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5/25/2013 10:05 P.M. ET

D-backs undecided on pitching order for doubleheader

PHOENIX -- D-backs manager Kirk Gibson knows Trevor Cahill and Ian Kennedy will both pitch in Monday's split doubleheader against the Rangers, he just isn't sure who will start the day game and who will start the nightcap.

"I don't know what order they'll be in," Gibson said. "We've had some conversations about it but I don't have it right now."

Kennedy last pitched on Tuesday so he will be on six days' rest Monday while Cahill's last outing came on Wednesday, so he'll still be on his normal schedule thanks to Thursday's off-day.

For the Rangers, they've already established that left-hander Martin Perez will work the first game and staff ace Yu Darvish will take the mound in the evening.

Putz resumes throwing, won't be rushed back

PHOENIX -- Two and a half weeks after being diagnosed with a sprained ulnar collateral ligament in his throwing elbow, D-backs closer J.J. Putz has begun playing catch on flat ground, the first step in returning to the Arizona bullpen.

"He has thrown three times, he threw from 90 feet yesterday," D-backs manager Kirk Gibson said. "He's feeling good, he says his arm feels good."

Gibson isn't sure when Putz, on the 15-day disabled list since May 8, will start throwing on a mound again, but he said the club doesn't want to rush the 36-year-old back too soon.

"It'll be something we take our time on, he'll probably want to go faster than we're going to go," Gibson said. "We want to make sure we strengthen him right, he's done a lot of exercises. We try to get them ready stamina-wise."

In 2011, Putz endured a similar injury to his elbow and missed exactly four weeks from June 29 to July 26.

Before getting hurt, Putz held a 4.26 ERA in 12 2/3 innings while converting just five of nine save chances.

Corbin using new mouthpiece on his stellar run

PHOENIX -- If you've watched Patrick Corbin throw this season, you've probably noticed the left-hander chewing on a mouthguard during his outings.

That's something new for Corbin, who began wearing the piece this season. A representative from the company Pure Power Mouthguard visited to the D-backs earlier this year and convinced the 23-year-old that using one could help him on the mound.

"He gave a good spiel and sold me on it, so I got one custom-made," Corbin said. "I just wanted to try it out and I probably started using it in my third or fourth start."

The mouthguards are supposed to align a player's jaw with his center of gravity, thereby reducing muscle tension in the neck, shoulders and back. Theoretically, all of that is supposed to translate into an uptick in a pitcher's velocity, which Corbin has actually seen this season en route to a 7-0, 1.44 ERA start.

Corbin's average fastball velocity is around 1 mph faster in 2013 from last year, ranging from 91-94 and sometimes touching 95. Even though he was reaching those higher speeds before he began using the mouthguard, Corbin still believes it has assisted him, even if only mentally.

"Anything that can help a little bit, I'm all for it," he said. "It keeps my mind off things. I don't know if it really helps or not, but I like it a lot."

Snake bites

• With Willie Bloomquist (oblique) inching closer to a return from the disabled list, the D-backs are beginning to talk internally about what will happen to their roster when the veteran infielder comes back.

"Bloomquist is the closest, so we've had light conversations about the roster construction and the moves that need to be made," D-backs manager Kirk Gibson said. "But you don't spend a lot of time on it because someone may get hurt."

In his first rehab game with Triple-A Reno on Friday, Bloomquist went 2-for-4 with four RBIs and a run scored.

• Entering Saturday's action, the D-backs hadn't hit a home run in their past seven games. Even without the use of the long ball, the club holds the third-longest streak in the Majors with at least one extra-base hit in 32 consecutive games.

Tyler Emerick is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.