"We're not going to bring him back if he's not ready to be 100 percent," Gibson said. "That's why we put him on [the disabled list] and we'll have to wait until it's fully gone."
• The D-backs have not announced who will start for them in next week's two-game series against the Rays on Tuesday and Wednesday. The team is off on Monday, so it could skip a starter if it wanted.
Zeke Spruill was called up from Triple-A Reno to start Thursday against the Rangers, but the team has not decided whether he will get another start or be sent back down.
Brandon McCarthy is slated to come off the disabled list to start Sunday, while Trevor Cahill is supposed to make another injury rehab start Monday for Reno.
"Just day to day," Towers said of the rotation. "We have an off-day where you can kind of change things. Cahill is throwing again on Monday. We'll see how he does. We don't have to make a decision right off the bat. How McCarthy looks on Sunday, too. Where we're at, we have so many new pieces coming in, I hate to commit right away."
• Recently demoted left-hander Tyler Skaggs is not throwing as hard as he did a couple years ago, but Towers said that was a matter of mechanics not health.
"You wouldn't be able to throw the curveball with the torque that he has if his arm was bothering him," Towers said. "I think it's mechanical. We tried to look at delivery. He's more upright and not getting out over his front leg. He was kind of crouched when he was in the Futures Game a couple years ago and now he's more straight up and down."
Better fastball command is something the D-backs would like to see from Skaggs.
"He relies too much now on his secondary stuff," Towers said. "He has a great breaking ball and change-up, but in order to be effective up here, he has to have much more confidence in his fastball and be able to use his fastball more."
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.