"It's one of those deals that whenever you're cleared to throw, it's a big day for you," Wacha said. "Whenever you're cleared for your first 'pen, it's a big day. But I know it's still a long road to go. I'll keep working hard and stay the course.
"It felt good to get back out there on the mound, the first time in a while. My arm felt great."
Pitching at low intensity, Wacha threw mostly fastballs, mixing in a few changeups as well. He is still scheduled to have a follow-up MRI on Monday so that doctors can ensure that Wacha's shoulder is continuing to heal. As long as everything checks out positively, he's expected to continue throwing off the mound every two-to-three days for some time.
"It's a great thing to see," manager Mike Matheny said. "It's a step forward. We're not putting too much pressure on him. I know it's just another step in the process. He has to trust it and keep moving forward."
Whether he heads out on a rehab assignment will be determined by whether he progresses quickly enough to join one of the affiliates before the Minor League regular season ends on Sept. 1. Wacha could also build up his arm strength by throwing simulated games in St. Louis.
"There's definitely been anxiousness," Wacha said. "You want to get out here and want to start throwing, but I understand that you have to take your time with these kinds of injuries. It's important not to rush back too quickly. That's how I've been dealing with it mentally and understanding long-term goals as well."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.