"It came on a combination of probably a few pitches," he said. "Just kind of tightened up, a little cramp, and it got a little worse."
The Astros know all too well how long muscle strains on the side of the torso can linger. Outfielder Alex Presley has been out for more than a month with an oblique strain, outfielder Dexter Fowler missed 40 games with an intercostal strain and pitcher Anthony Bass missed 47 games with an intercostal strain.
"From my understanding, it's really minor," manager Bo Porter said. "I didn't want to take any chances looking at the history we've had with those things so far this year, with Bass, Fowler and Presley. You look up and they miss considerable time. Instead of playing short in the bullpen, it was to our advantage to get somebody here."
Downs had a more several oblique injury in 2006 that made it difficult for him to breathe or roll over in bed. This is nowhere nearly as bad.
"This is kind of a little cramp," he said. "We'll see how it goes the next couple of days."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.