"A convergence of circumstances sent Ryan Ludwick to the disabled list.

Ludwick said he experienced back spasms Tuesday, then again Wednesday morning. He has had these back spasms before in his career, he said, but usually in the offseason.

"Usually they'll put me on some muscle relaxers and it goes away in 48 hours," he said.

On Wednesday, he had an MRI that showed no damage, but was put on the disabled list.

"I don't think that he had a second episode in the past, which is what was challenging for us," general manager Neal Huntington said. "Our thought was the second episode was going to make it unlikely for him to be able to play through the weekend, which would leave us short for a week."

The Pirates had to make a roster move Wednesday to add spot starter Aaron Thompson to the active roster. They could have optioned Pedro Ciriaco to Class AAA Indianapolis, but then they would have been two bench players short with Ludwick also unavailable."