The D-backs acquired left-hander Joe Thatcher just prior to Wednesday's non-waiver Trade Deadline, and he now fills the left-handed specialist role.
"I think we view Thatcher as a better alternative as a left-handed guy," manager Kirk Gibson said.
Sipp was 3-1 with a 3.86 ERA, but the biggest concern was the fact that he walked 18 in 32 2/3 innings.
"If I feel sorry for myself, obviously it's going to have a negative effect on me," Sipp said. "The positive thing is right now ... I'm starting to feel like my old self, throwing strikes again. I feel like my stuff is better or getting better. Just have to continue to get better and take those steps towards the right direction."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.