Hazen added that Walker has had to adjust his repertoire in his last few starts to work around the blister. By putting him on the DL now, the team is hopeful that the blister will heal.
"It varied between changeup, slider and even fastball, at times, where he feels it," Hazen said.
Walker tossed six shutout innings Friday night against the Padres and was scheduled to start again Wednesday afternoon against the White Sox at Chase Field. The D-backs have not said who will start in his place.
"That's all still TBD," Hazen said. "We haven't had a chance to really sit down and walk through that yet. We'll obviously have until Wednesday to figure out what we want to sort of do."
The D-backs could call up a starter from the Minor Leagues, but it's also possible they could use a handful of relievers to get through Wednesday's game. Randall Delgado, Archie Bradley, T.J. McFarland and Tom Wilhelmsen are all capable of throwing multiple innings.
Walker is 4-3 with a 3.46 ERA in nine starts this season. He was acquired by the D-backs along with Ketel Marte in December from the Mariners in a trade that sent Jean Segura and Mitch Haniger to Seattle.
McFarland, who had been on the 10-day DL with a left ankle contusion, was activated Sunday.
Steve Gilbert has covered the D-backs for MLB.com since 2001. Follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.