"Everything felt really good," Walker said. "I still threw with the tape on, so I didn't get a real feel for it, but mechanically I thought it was the best I've felt all year."
Walker has thrown with tape covering the blister so as not to aggravate it any further. On Wednesday he threw between 60 and 65 pitches.
D-backs manager Torey Lovullo said the team would evaluate Walker in the next 24-48 hours and then decide whether his next step will be to rejoin the rotation or if he needs to give the blister more time to heal.