Obviously, there was something wrong. Casilla's only other run allowed on the season had come five days earlier in Texas. He had not been scored upon in 18 innings of work before then.
Sure enough, he immediately went to a doctor in Cleveland, who, after just one small pinch of his sore right elbow, told the 27-year-old he would be out for the remainder of the season.
News travels quickly -- especially bad news -- as evidenced by a disappointed Bob Geren talking soon after about how his pitcher's outlook wasn't too bright.
The A's placed the pitcher on the 15-day disabled list Friday, but luckily for Geren and Oakland fans, the Cleveland doctor's accuracy was about as inaccurate as Casilla's pitch that landed in the Progressive Field stands.
Following Monday's game, Geren announced Casilla had been diagnosed by a local doctor with a "mild" ligament strain in his right elbow and would be allowed to start a throwing program in five days.
"That's real good news," Geren said before Tuesday's game against Tampa Bay. "I just talked to him, and he's doing well."
Casilla, who boasts a 2-0 record with a 0.93 ERA with 22 strikeouts through 19 1/3 innings, appeared optimistic about his return to the mound, despite a large bandage wrapped around his elbow.
"Hopefully in about 3-4 days, I can start throwing the baseball again," Casilla said. "I was told I'd be softly tossing the ball from about 10-15 feet away."
Casilla said the workout plan after that has yet to be determined, but he knows what he'll be doing on his end.
"I just need to take it easy," Casilla said, "and ice it as much as I can."
Jane Lee is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.