"It was an area that we felt to be able to compete with the team that was right in front of us we needed to strengthen our bullpen, and moving Brandon and Jordan allowed us to get an experienced reliever, which was important to us," D-backs GM Kevin Towers said.
The side-arming right-hander was 3-2 with a 2.39 ERA in 43 games for the A's this season and is 11-13 with a 2.49 ERA in 223 games over his four-year career.
"I'm excited to jump into a pennant race knowing that they gave up a couple guys that the A's are really high on, that the D-backs are really high on, too," Ziegler said. "I feel like I'm going into a situation where they appear to want me, where they appear to think I'm a piece to help them get over the top and hopefully make a playoff run in the last two months."
The backend of the D-backs bullpen has been a strength this year with setup man David Hernandez and closer J.J. Putz providing a solid one-two punch. However past those two, however, the team has struggled to find consistency.
Additional depth was also a need given that this is Hernandez's first year as reliever and the team wants to make sure he can handle the intense workload.
"He definitely will help the bullpen," Putz said of Ziegler. "He's a guy that can pitch in many different situations. Kills righties. He just gives [manager Kirk Gibson] another weapon to mix and match to get to David and myself. I think it's a good move."
Ziegler has held righties to a .198 average this year and to a .224 mark over his career. Lefties, by contrast, have hit him at a .396 clip this year and .325 in his career.
Towers has long been a believer in having bullpens with different styles of pitchers. Having a right-handed submarine style pitcher to go with Joe Paterson, who provides that look from the left side, fits that mindset.
The 31-year-old Ziegler garnered national attention in 2008 when he set the Major League record for scoreless innings to begin a career at 39.
While the pair of moves helped to strengthen the roster, they also sent a message to the players that the front office is serious about winning this year.
"It says we expect to keep on doing what we're doing," Putz said. "They all thought that K.T. was aggressive, but aggressively smart -- and I think he's proved that."
The D-backs' main rival in the division got better at the Deadline as well, with the Giants acquiring outfielder Carlos Beltran and shortstop Orlando Cabrera.
"I think they respect the way our club plays," Towers said. "I think their hope was maybe with the Beltran deal, the Cabrera deal that maybe the rest of us would just fade away. We wouldn't have made these moves if we didn't at least make it feel like we could make it difficult for them. They're a very talented ballclub and they're the world champions."
The Ziegler deal comes on the heels of the club's acquisition of Marquis, who will start Wednesday against the Giants.
To make room for Marquis the club will need to move one of its starters to the bullpen. That will likely be Micah Owings, who started Saturday, but neither Gibson nor Towers was willing to say that Sunday.
In addition there will need to be a couple of pitchers taken off the 25-man roster, decisions Gibson said had yet to be made.
Double-A first baseman Paul Goldschmidt was expected to be promoted to the big leagues to take Allen's place on the roster.
Trades can still take place until Aug. 31, but the players involved must clear waivers before being dealt.
"It's not to say that we're done," Towers said. "I think August is always an interesting time too to continue to look to add to your club if you can."