"It still needs a little work, but I felt, for my first time throwing curveballs off the mound, I did pretty well with it," Walker said after snapping off about 10 benders.
The youngster has been itching to get back into game action and did the best he could in that regard Wednesday.
"I faced some imaginary hitters," he said. "I was in that mindset, that game mode, and it felt really good. So I was pumped about that and I let loose a little bit."
Walker said he didn't put any names or faces to his pretend foes, just pictured a right-hander and then a lefty in the box.
Did they get any good swings at his offerings?
"No, I think I had two strikeouts," Walker said with a grin. "Only needed six pitches."
Walker said he "had a smile on my face again" after his session, but the last few weeks haven't been easy for a youngster who came to camp hoping to crack the opening rotation before his shoulder began hurting.
"It's tough," he said. "Every day when I wasn't throwing for seven days I wanted to pick up a ball and just chuck it and see how it felt. But I know I just have to listen to what the trainers say. They're really good at what they do, and know I'll be healthy when I'm ready."
Walker said he's scheduled to play catch Thursday to see how the shoulder responds, then will see what's next. In Walker's mind, pitching to live hitters can't be too far away.
"I think so," he said. "My last three bullpens have been really good. The one before this was one of the best of my career, just the way I was locating, and my arm strength is up there pretty good, too. So I think I'm pretty close."