"If he wasn't feeling so much better, and the results wouldn't have been so good throwing so far, we would have shut him down," Pirates manager Clint Hurdle said. "But he was convinced he just needed a blow. We wanted see how his arm would respond. There is no discomfort and he wants to get back on the mound, and we're going to give him that opportunity. We definitely don't want to push it, but there's no red flags since we set him down, and since the fatigue he felt in the last outing when he was running out of gas."
Karstens threw a bullpen on Wednesday.
"It went really well," Karstens said. "It was nice to get back out there and try and get some of this rust off, and a couple of bullpen outings and I'll be back on the mound. Everything feels really good."