Webb, who is attempting to return from shoulder surgery performed last August, faced hitters for the first time since throwing a simulated game last Saturday in San Francisco, which was the first time he had faced hitters since Opening Day of 2009. Following that outing he was encouraged after throwing 52 pitches.
On Friday, he had hoped to build off that effort, but instead threw around 35 pitches and lacked command of his pitches.
"It wasn't as good as it was the last time," Webb said. "I was as wild as I've ever been. I had no clue where it was going. I was a little disappointed because I felt like it went pretty good last time."
The issue, Friday Webb said, was his mechanics as he tried starting with the ball out of his glove in an attempt to help improve his arm speed, which was lacking.
"I felt like I should have been able to bump it up a little more than last time, but didn't," Webb said. "I think a lot of it was mechanical. I just wasn't throwing strikes. I'm still not reaching out in front and getting it out in front of me."
The positive from throwing fewer pitches is that Webb will likely be able to get back on the mound quicker this time around. He said he was aiming for facing hitters against Tuesday or Wednesday and he is still hopeful of making a few appearances out of the bullpen before the end of the season.
"Anything I can grab out there would be great," he said. "We have a little bit of time left. I'm going to have to have a couple more miles an hour. I was 82 last time. I think 84 or 85 would get the job done so hopefully I'll be able to reach that in a couple more times out."
D-backs interim manager Kirk Gibson said he would not describe the session as a setback for Webb.
"He didn't throw as good as he did his last time," Gibson said. "I cautioned you guys about that last time. I've been through enough rehabs to know that you get excited and it's possible to have a day that's not what you're expecting it to be. I consider it normal. That's why I caution you guys not to put expectations on it."