ATLANTA -- Seeing a D-backs player atop the National League strikeout chart is not a new development. After all, third baseman Mark Reynolds has set the Major League record for whiffs in each of the past two seasons.

But right now it's teammate Justin Upton that leads the NL with 47 strikeouts heading into Friday's action.

"It's going to be part of his game, but it shouldn't be dominating his game like it is now," D-backs manager A.J. Hinch said. "It all comes down to pitch selection. Right now, at least the last two weeks, even when he's scratched out his hits, he's been a little late on the fastball -- a little early on the breaking ball, which is a vicious cycle to get out of."

Upton's struggles have come at the same time the Arizona offense is trying to recapture its early-season potent production.

On the just-completed 0-6 homestand, the team as a whole hit .195 with 61 strikeouts.

"He's out of sorts, he's been out of sorts, swinging outside the zone a lot," Hinch said. "He's taken it upon himself to swing his way out of this slump, and it's caused him to get out of his discipline."

D-backs starter for Tuesday still up in the air

ATLANTA -- The D-backs will start right-hander Edwin Jackson in the opener of a two-game series with the Marlins on Monday.

Tuesday's starter is listed as TBD, or to be determined.

"It is what it is, TBD," D-backs manager A.J. Hinch said.

It would be Cesar Valdez's turn in the rotation after the club skipped his last start due to Thursday's off-day. In two starts since being called up from Triple-A Reno, Valdez is 1-1 with a 7.00 ERA, and the right-hander is currently available to help out the struggling bullpen if needed.

"Some of it depends on how the bullpen shakes out here," Hinch said when asked who was being thought of for Tuesday's start. "There's a name or two we are considering, but nothing that we have to worry about until we get past this weekend."

As for speculation that the team could move Valdez to the bullpen permanently, that does not seem to be the first option.

"It's more of a long-term question," Hinch said. "It's a consideration. I think it's possible."

Montero jogs on field for first time since injury

ATLANTA -- Patience is hard to come by these days for Miguel Montero.

The D-backs catcher is anxious to get back on the field after having surgery to repair a torn meniscus in his right knee, which he injured April 11.

Friday marked another step forward for Montero, as he jogged on the field for the first time since the injury.

"It was just an easy jog," he said. "Did some side-to-sides, jogged a little backwards. It feels really good, actually. Obviously, it was just at a nice and easy pace, but it was nice to get out there."

Montero said he will take batting practice on the field for the first time Monday in Florida, and he hopes by the time the D-backs go on their next road trip (May 25-June 2) that he will be able to head out on a Minor League rehab assignment.