"Our bullpen has been overworked, so to be able to add additional arms, that'll help us spread it around a little bit and keep guys fresher," manager Kirk Gibson said. "I just don't want to get to the point where guys are throwing four out of five days again unless we have to. We've had a fair amount of that in the last month."
In Hernandez and Sipp, the D-backs are adding a pair of relievers who figured to be mainstays with the club this year, but instead endured disappointing results and were both optioned near the beginning of August.
"They have a ton of Major League experience; we just sent them down to kind of get them work on a few things," Gibson said. "They both threw the ball pretty decent down there, too."
Hernandez was arguably the D-backs' most reliable reliever in 2012, posting a 2.50 ERA over 68 1/3 innings. In 2013, however, the right-hander surrendered 30 earned runs in 48 1/3 innings (5.59 ERA) before his demotion, allowing more home runs (10) than he had in his previous two campaigns combined (eight). The 28-year-old made nine appearances for Reno, allowing one run over 9 2/3 innings.
"I tweaked a few things, just trying to get back to basics," Hernandez said. "With all the pressure to perform, I kind of got away from just having fun. I felt like I improved on a lot of things and I started having fun again. I know every outing I'm not going to be perfect, it's just about consistency."
By the numbers, Sipp wasn't having a terrible season when the D-backs optioned him, as he had a 3.86 ERA. But the southpaw was supposed to be the team's left-handed specialist and he actually proved to be more effective against right-handed hitters, holding them to a .210 mark while lefties hit .250 against him. So when Arizona acquired left-hander Joe Thatcher at the non-waiver Trade Deadline, Sipp's role in the bullpen was taken away.
Another concern the D-backs had was that he issued 18 walks in 32 2/3 innings. In nine games for Reno, Sipp allowed one unearned run in 10 innings, but he walked five batters.
"I felt like I was making a step in the right direction when I got sent down, so it was just a matter of what are you going to do? If you go down and pout about it, it almost justifies the reason for getting sent down," Sipp said. "So I chose to continue to make progress and throw strikes. It's a blessing just to start turning things around."
Hernandez and Sipp arrived in Arizona on Sunday around 11:30 a.m. MST, and just a few hours later, the D-backs called on Sipp to work the eighth inning against the Giants. He walked the first batter he faced but then retired the next three in order to escape the frame.
"I felt good, kind of got off the plane and onto the mound, I didn't play catch or anything," Sipp said. "My first couple throws were on the mound; everything happened so fast, but it definitely felt good to be back."
The D-backs expect to call up a few more players from Reno on Tuesday, the day after the Aces' season ends.