McCullers (back) was activated from the 10-day disabled list and confirmed as the starting pitcher for Wednesday's game against the Mariners.
As expected, McCullers will rejoin the Astros' rotation ahead of his first big-league start since landing on the shelf at the end of July. The 23-year-old was able to toss 60 pitches in a five-inning rehab outing last week, followed by a 15-pitch simulated inning in the bullpen, so he shouldn't be facing much of a pitch limit in his first start back. McCullers struggled in July before hitting the DL, but he still owns a respectable 3.92 ERA and 118 strikeouts in 105.2 innings this season.