"Over the course of the next week, we'll assess a plan based on further tests, further examination," manager A.J. Hinch said Friday before the Diamondbacks played the Mariners.
Hinch said Arizona sent its 22-game winner home from its road trip instead of waiting until doctors were available next week to clear his mind. He's made just one start this season and has been on the disabled list since April 13.
"I mean, this guy's been battling a long time to get back on the field, with a scheduled side session as early as [Friday]. So it's a pretty emotional time for him to have pain in his shoulder," Hinch said. "Just go home and clear his mind a little bit and take a breath away from a pretty rigorous rehab program that he's been on, and gear toward getting back on the mound.
"He had pain. It's time to go home and get tested."
Webb's shoulder bothered him Thursday while playing catch on flat ground in Kansas City. The team canceled a bullpen session for Friday in Seattle, leaving his comeback in limbo.
Webb has won at least 14 games each of the previous four seasons.
"I feel bad for him," teammate Dan Haren said soon after Webb left. "I couldn't imagine how frustrated he is. He and everybody wants an answer and he hasn't really been able to get it. It is nobody's fault. It's been real hard for him. He's in the trainer's room and doing these drills and it's just not getting better."
Also Friday, the Diamondbacks activated Tony Clark from the disabled list. The veteran infielder missed 41 games with a sprained hand.
Clark was in the lineup at first base and batting sixth Friday night. He turned 37 while he was on a seven-game rehabilitation assignment at Triple-A Reno, where he was 4 for 25 (.160) with a home run and two RBIs.
He was batting .179 with two homers and five RBIs in 17 games with Arizona before the switch-hitter sprained a ligament on his right hand.
Arizona optioned infielder Josh Whitesell to Reno to make roster room for Clark. Whitesell batted .214 in 20 games with the Diamondbacks.
Center fielder Chris Young was out of Friday's lineup, but Hinch said Young was feeling much better. He left Thursday's night win at Kansas City after he strained a groin muscle while running during his career-high fourth hit.
Hinch is weighing resting Young all weekend to get him four days off -- Arizona has an off day Monday -- or using Young as either a designated hitter or in the outfield as early as Saturday.