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8/3/2014 1:15 P.M. ET

Diaz earning more responsibility in Reds' bullpen

MIAMI -- The way Reds reliever Jumbo Diaz has pitched since his first callup following 12 seasons of Minor League baseball, it's easy to wonder why the 30-year-old wasn't promoted sooner.

Following a rocky debut vs. Toronto on June 20, Diaz entered Sunday with a 1.23 ERA with two earned runs allowed over 14 2/3 innings. On Saturday vs. the Marlins, the right-hander worked 1 2/3 scoreless innings before Cincinnati lost 2-1 in 10 innings.

"It's impressive. The thing that's unusual -- I think the stuff has always been there," Reds manager Bryan Price said on Sunday. "He's always had the velocity. There's nothing new to the velocity; he throws strikes. He has three pitches, he gets lefties out.

"I don't know if it was just the weight and they didn't want to put him out there at 340, 350 pounds or if he's just been more efficient with the weight loss. I know he ran some really good numbers for us before the weight loss -- noteworthy numbers -- but he was never really a topic of conversation whenever we talked about guys in our system at being options of helping us at this level."

Diaz dropped from 347 pounds to 278 pounds in the past offseason, a drop of 69 pounds.

As he's pitched well, Diaz has gotten to work in more and more high-profile situations. He was used Saturday to finish the eighth inning and work the ninth as Jonathan Broxton was unavailable. Price isn't afraid to use him to set up, or even to close, should Aroldis Chapman or Broxton not be available.

"The other part of it that has been impressive has been his demeanor," Price said. "Maybe that's just the maturity of a 30-year-old man with a lot of life experience in this game. He's embraced this opportunity. He's early to the ballpark, he's not cavalier about it. He's been very, very focused on maintaining his in-season shape and fitness. … We haven't been as consistent out of our bullpen in 2014 as we were in '12 and '13, so he's given us a real boost."

Parra's back tested fielding bunt single

MIAMI -- Whether he realized it at the time or not, Reds lefty reliever Manny Parra had to test his recently injured back in his first outing back after a long layoff.

Parra, who pitched for the first time since July 20 on Saturday vs. the Marlins after back spasms kept him out, had to bend over to field a perfectly executed two-out bunt single from Jordany Valdespin in the eighth inning that rolled between the mound and the first-base line.

"I guess I didn't think about it, so that's good. I wasn't worried about it. It was just a great bunt," Parra said on Sunday.

Taking over in a tight 1-1 game, Parra had already retired the first two batters he faced, including leadoff batter and pinch-hitter Donovan Solano with a strikeout. Parra exited after Valdespin's hit.

"As soon as the pitcher's spot was leading off, the guy who was going to hit, we knew it'd be Solano because he was 2-for-4 with two doubles off of [Parra]," Reds manager Bryan Price said. "And then he comes in there and makes some great pitches to get him out, [after] almost two weeks of inactivity. It's not like he's been able to go out there and throw bullpens and keep his delivery in shape. It was a very impressive outing."

"It's interesting to go out there after that long. It was a big situation, so I wasn't thinking about that, but afterwards, I was pretty happy," said Parra, who hasn't allowed a run since May 25.

Hannahan ready to contribute wherever he can

MIAMI -- Reds backup first baseman Jack Hannahan has been off of the disabled list for one week as of Sunday, and has reported no issues with his surgically repaired right shoulder. Hannahan had missed all season until his July 27 activation.

"It's good. It's something I feel like I can maintain and fill in where they need me to give guys breaks or come up and pinch-hit," Hannahan said. "It's at the point where it's going to be until I can get to the offseason and give it the proper rest it needs to completely bounce back."

Hannahan, who usually plays third base also, has yet to make any throws across the diamond. But the Reds needed a veteran hitter, and his shoulder had improved just enough to allow him to play first base and hit. He can throw pain-free from first base.

Through four games, including two starts, Hannahan was 0-for-9 with four strikeouts.

"In the situation we were in, I felt comfortable throwing to turn a double play from first base," Hannahan said. "I felt comfortable swinging the bat. It's what they needed up here. I'm confident that can strengthen up my arm to where I can give Todd [Frazier] a break over at third base if he needs one, later in the year."

Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.