MIAMI -- Left-hander Mike Dunn does not have a defined role in the Marlins' bullpen this season. Other than closer Steve Cishek, nobody does.
But the uncertainty keeps Dunn and his teammates on their toes.
"Everyone's just kind of ready to go whenever the phone rings," Dunn said. "We've got different guys going multiple innings. We've got guys pitching just about every inning. So, it's just basically making sure you're stretched and ready to go. When the phone rings, be ready to pitch."
In Sunday's 2-1 win over the D-backs, Dunn was called on to get the final out after Cishek left with runners on first and second and two outs. Dunn was brought on to face left-handed hitting Miguel Montero, who he walked to load the bases, but then got pinch-hitter A.J. Collmenter to ground out to short to end it for his second career save and first this year.
Miami's bullpen ranks fourth in the National League with 143 innings pitched entering Sunday's game against the D-backs. Seven relievers have tossed more than 11 innings, and Wade LeBlanc recently joined the fray with six innings out of the bullpen during the past week.
The Marlins designated reliever Jon Rauch for assignment late Friday and recalled left-hander Duane Below from Triple-A New Orleans. Manager Mike Redmond said Saturday he anticipated using Below in a long relief role similar to that of LeBlanc.
However, Redmond also said Below could be used in situational at-bats against left-handed batters, playing into the constantly changing roles in Miami's bullpen.
"If you're watching the game, you can understand what guys are probably going to be getting the call just by who's coming up for the other team," Dunn said. "It's not necessarily a specific inning that someone's going to pitch."
Although his role is not clearly defined, Dunn has become one of Miami's most reliable relief pitchers this season. He ranks second on the team with a 1.77 ERA and his 20 1/3 innings are the third highest total among Marlins relievers.
Dunn has proven especially productive at home, pitching 10 scoreless innings at Marlins Park.
"Every game's the same. It's just attack the hitters," Dunn said. "Whether it be at home or the road, I feel like I'm having a good year all around. It doesn't really matter where we're at. You've just got to go out and do your job no matter where it is."
Koehler looking for consistent command
MIAMI -- What Tom Koehler's latest start revealed is that the right-hander has the pure stuff to be successful in the big leagues. The question that still needs to be addressed is whether the 26-year-old can consistently show command.
When he does, he's impressive.
Koehler had a career night on Saturday, even though he came out on the losing end of the Marlins' 1-0 decision to the D-backs.
One pitch -- his first of the night -- haunted Koehler, as Gerardo Parra belted Koehler's 94-mph fastball over the wall in right field. Besides that, it was a promising second start of the season for the New Rochelle, N.Y., native.
"I'm happy with the command," Miami manager Mike Redmond said. "I think we were always, maybe in Spring Training, a little bit worried about his command and how he'd command the strike zone.
"But he's come up and just done a nice job. I think what I'm most impressed with is how he's been able to use that curveball to kind of get his fastball down in the zone and be a nice secondary pitch for him. As he goes through a lineup for the second and third time, he's got that as a weapon, and he's been able to command it, and that's the key. He's been able to do that the last couple of days. It was fun watching him."
Koehler struck out seven in six innings.
Arizona manager Kirk Gibson was impressed.
"He's got a good arm, very lively arm, and he had good velocity," Gibson said.
Since joining the rotation, Koehler has a 2.45 ERA with eight strikeouts in 11 innings.
He walked two and had a number of deep counts, which raised his pitch count to 94. Being more economical with his pitches remains a point of focus.
"I hope next time I can limit the pitch count a little more, and eliminate some of those three-ball counts, and try to get into the seventh and eighth innings," Koehler said.
Stanton received plasma injection in hamstring
MIAMI -- To help the recovery process, Giancarlo Stanton received a platelet-rich plasma injection shortly after he strained his right hamstring late last month.
In recent years, platelet-rich plasma (PRP) injections have become more popular in all sports.
Arizona outfielder Cody Ross, formerly with the Marlins, was on the ground floor of the PRP injections, receiving one during his days in South Florida. After being bothered by hamstring injuries in 2007, Ross had the PRP injection, and in 2008, he remained healthy and productive.
"It really helped with recovery," Ross said on Sunday.
The procedure basically is as follows: the patient's blood is drawn, and treated, and then injected back into the inflamed area. Carl Crawford received a PRP injection last year. Golfer Tiger Woods and NBA star Kobe Bryant also have had similar treatment.
Stanton, Miami's 23-year-old slugger, strained his right hamstring on April 29, and Sunday marked the 18th straight game the All-Star right fielder has missed.
Stanton said he was given a PRP injection in Miami a day or two after he sustained a Grade 2 hamstring strain.
"It promotes recovery a little quicker, especially if there is a lot of inflammation in that area," Stanton said.
Stanton still remains several weeks away from returning. He is throwing, hitting and running on an anti-gravity treadmill.
• Logan Morrison will begin his rehab assignment with Class A Jupiter on Monday. Eligible to be reinstated from the 60-day disabled list on May 30, Morrison expects to play about a week with the Hammerheads before going to Double-A Jacksonville and eventually Triple-A New Orleans. The left-handed hitting first baseman is recovering from right knee surgery.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. Joe Morgan is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.