
Osuna was acquired from the Toronto Blue Jays in a trade-deadline deal last week and is coming off a 75-day MLB-imposed suspension for violation of the league's domestic violence policy.
Houston released a statement on Osuna's activation on Sunday afternoon.
The Astros released the following statement: <a href="https://t.co/y7ijZ3nzHw">pic.twitter.com/y7ijZ3nzHw</a>
—@astros
McCullers pitched four scoreless innings Saturday against the Dodgers but left as he warmed up for the fifth inning.
Astros manager A.J. Hinch said he will take advantage of some upcoming days off and go with a four-man rotation through the middle of August.
McCullers returned to Houston on Sunday morning to get a more detailed examination from team doctors.
McCullers is 10-6 for the World Series champion Astros with a 3.93 ERA in 22 starts.
