PHOENIX -- On Monday, D-backs infielder Geoff Blum was on the diamond at Chase Field.

Blum, progressing back to the active roster after suffering a broken finger on July 24 against the Rockies, speculates it will take him two more weeks to get back healthy.

"It felt good," he said. "I can't speed up Mother Nature, but I'm doing the best I can."

Blum fractured his right pinky finger fielding a ground ball and was forced to the disabled list for the second time this season.

In addition to continuing a lower-body workout Monday, the veteran took ground balls and fungoes from D-backs third-base coach Matt Williams.

"I've been doing a lot of conditioning and stuff like that to stay in shape and do the things that I can," Blum said. "Obviously, I can't swing a bat, but hopefully here in about a week and a half to two weeks, I'll be able to do that."

D-backs manager Kirk Gibson said Blum is scheduled to have another X-ray in around a week's time.

"We'll get a better idea on when he can start to move it then," Gibson said.

Blum is hitting .200 (3-for-15) in seven games this season.

Collmenter trying to rediscover mojo

PHOENIX -- Josh Collmenter is getting back to basics.

"Working the ball down in the zone," Collmenter said of what he's been focusing on. "When I work down in the zone, everything plays off that. If I can keep my fastball location, then it makes the changeup and curveball that much better."

Collmenter has stumbled upon tough times, losing two consecutive starts -- both to the Dodgers -- and getting chased in the third inning of Friday night's 7-4 loss.

After starting the season 3-1 in his first four starts, the rookie right-hander has gone 3-6 since.

"He needs to execute his pitches better," D-backs manager Kirk Gibson said. "He needs to command his fastball better, and the last couple times out he just hasn't had his fastball command."

The 25-year-old is 6-7 on the season with a 3.58 ERA.

"For me, it's just making sure I don't get too far away from what I'm comfortable with and what I do well," Collmenter said. "Sometimes I shy away from that a little bit and try to be too perfect."

And while Gibson said Collmenter is still in the D-backs rotation -- "He's our fifth starter and he hasn't lost his job," the manager said Sunday -- Collmenter said he doesn't worry about things he can't control.

"I know they're going to put the best team out there to win," he said. "And I just want to make sure that I prepare myself every time to be one of those guys."

Ground ball is Marquis' best friend

PHOENIX -- The way Jason Marquis looks at it, if he's doing his job Tuesday night then the hitter-friendly reputation of Chase Field won't matter.

"The ultimate key for me is keeping the ball on the ground," he said. "Obviously anything in the air is not a good sign, but if I'm doing what I'm supposed to do then that doesn't come into play."

Marquis did what he was supposed to do in his first start, a shellacking at the hands of the Giants last Wednesday, in which the veteran gave up eight runs -- seven earned -- on 10 hits.

In that outing, ground ball after ground ball found hole after hole, which resulted in Marquis getting charged with the loss in his Arizona debut.

D-backs manager Kirk Gibson talked about the need for better defensive positioning when Marquis is on the hill.

"It's really just having an understanding of what he's trying to do to them, and then he gives us an idea of what he expects them to do if he gets his pitch where he wants it," Gibson said. "We'll change things a little bit and be more communicative."

Gibson also said that Marquis has the ability to dictate moves on the field.

"I told him, if he wants to make a move [he can], and there's a lot of veteran guys like that, they'll move guys if they know what they're going to do with a guy," Gibson said.

Marquis entered Tuesday with an 0-4 record and 4.21 ERA in nine career starts at Chase Field.