Scotty Feldman apparently injured his knee meniscus during his most effective start of the season, and has recently had arthroscopic surgery to repair it. That normally means 3-6 weeks away from a mound - at best - so the Astros have had make a roster move to fill his spot.
Michael Feliz became the second pitcher to be promoted from AA Corpus Christi this year. He had made one appearance in Corpus, which involved giving up a home run to the first batter he faced, but settling in to mow down four innings' worth of NW Arkansas hitters, including 7 strikeouts.
The Astros say that Feliz will pitch out of the 'pen, so another move will need to be made prior to Feldman's next day in the pitching rotation, which is likely to be June 1 or June 2 (depending on when McHugh goes). Brett Oberholtzer is the likely candidate to step up, instead of making his second rehab start. Jake Buchanan and Sam Deduno are other, less likely options.
This move seems to be about giving Feliz a taste of the major leagues, with a near-certain outcome an option back to the minors with something to work on for the next few months. This move also tells me that Deduno isn't ready yet, and that McCullers will likely get more than two more starts unless he starts to really struggle. Obie's return is in a nick of time: it must also be said that Peacock continues to have rotten luck with injuries in 2015, at a time where he desperately needs to establish himself as a starter.