PHOENIX -- Despite seeing sustained progress from starter Josh Collmenter, D-backs manager Kirk Gibson admitted Wednesday the righty's negative results are starting to take their toll.

"We've seen improvement in every start," Gibson said. "We've showed confidence, but the results aren't there and that means something. We're not going to be able to continue to tolerate four runs in an inning, that's pretty tough when you're playing the Phillies, they don't give up four runs a game. It's a complex situation."

Collmenter cruised through the first three innings Tuesday against Philadelphia but ran into trouble the rest of his outing and allowed six earned runs on nine hits including two home runs.

Through four starts, his ERA sits at 9.82.

"It's coming out of his hand much better," Gibson said. "But can he get back to where he was? That's the question."

The majority of Collmenter's problems have come from lefties, who are batting .340 against him this season.

"Lefties are hitting the ball hard against him and they got on him [Tuesday]," Gibson said. "That's a concern."

Rehabbing Hudson to work out in Phoenix

PHOENIX -- After Thursday's off-day, the D-backs embark on a three-city 10-game road trip to Miami, Washington and New York. One player who won't make the East Coast swing is injured starter Daniel Hudson.

The right-hander went on the 15-day disabled list Saturday with a right shoulder impingement and will stay in Phoenix to work on his rehab at Salt River Fields.

"He hasn't thrown yet, right now it's treatment and strengthening his shoulder to try to get the stiffness out," manager Kirk Gibson said. "We always take our time and make sure they're 100 percent. You don't want to rush him back, even as much as you want to sometimes. I want to make sure they can participate in their regular roles."

Once the D-backs return to the Valley on May 7, Hudson is scheduled to throw a bullpen to evaluate where he is in his recovery.

"That's the initial plan," Gibson said. "That's if everything goes well."

Zagurski and Martinez make bigs

PHOENIX -- For D-backs relief pitchers Mike Zagurski and Joe Martinez, getting called up to the Major Leagues on Tuesday was special enough.

But what made the experience even better was going through it with a close friend. Zagurski and Martinez met at Spring Training and were roommates together on the road while at Triple-A Reno.

"It's more fun coming up with someone else that I'm also happy for," Martinez said. "It's cool because we hang out a lot already."

As early arrivals every day at Salt River Fields, the pair got to know each other while playing catch.

"We just became friends from there," Zagurski said. "It was nice, there's somebody to travel with and go through everything together with."

To top everything off, Reno manager Brett Butler broke the news to the friends together.

Zagurski was the first of the pair to pitch in a D-backs uniform, he threw an inning Monday against the Phillies, allowing a home run to Shane Victorino then retiring the next three batters.

"I didn't think my stuff was all that great with getting the ball where I wanted to but I got through it," Zagurski said. "One bad pitch which resulted in a homer, but it's going to happen. It's something to build on the next few days and hopefully get back in there soon."