"The second pitch of the inning I felt my forearm tighten up on me," said Schafer, who added that he felt the same discomfort in his previous outing on March 9 against Houston. "The last two outings, that forearm has been bothering me.
"It got to a point today where I really didn't feel comfortable trying to spin anything else off. So I was just trying to throw the ball over the plate and hopefully they would hit it at somebody and move on."
Making his fifth Grapefruit League appearance, Schafer came into the game having thrown a total of three innings, allowing two runs on five hits. Both runs were issued to Houston. He had gone three outings, spanning three innings prior without giving up a run.
But that was before the forearm muscle tightening.
"I don't think it's anything serious," Schafer said. "I just think it needs time to cool down a little bit. I think I'll be fine."
Schafer said he would see how he feels Monday and then make a decision accordingly as to whether to seek medical treatment or not.
"I usually can throw the ball pretty much where I want to, and in my head I was more worried about really letting go of the ball and how it felt than really focusing in on pitches I needed to make," he said of the abbreviated outing.
Never having had any arm problems in the past, Schafer said that in his transition from outfield to pitcher, he's really pushed himself early on in Spring Training. "I think the biggest thing is I haven't really had a chance to let it cool down," Schafer said. "Even when I don't throw, when I swing, that forearm muscle I'm using that same muscle.
"I don't think it's anything serious or anything to worry about. They gave me a test and everything was fine."
Glenn Sattell is a contributor to MLB.com and covered the Cardinals on Sunday.