Manaea is ranked as the A's No. 2 prospect and No. 65 in baseball by MLB Pipeline. The left-hander is 2-0 with a 1.50 ERA in three starts for Triple-A Nashville this season, having struck out 21 batters in 18 innings. The A's acquired Manaea in last season's trade with the Royals involving Ben Zobrist.
"[Manaea's numbers] look really good; we knew that," Melvin said. "We saw him in spring, got to see him long enough to know the talent level meets what our expectations were of him. He maybe exceeded it in spring. We knew, at some point in time, we'd be seeing him, whether it be earlier in the year or later."
Jesse Hahn was another candidate to come back up for the start, but Melvin said Manaea's numbers and a blister issue for Hahn gave the 24-year-old Manaea the nod.
This isn't likely to be a short-term promotion. Melvin said the A's plan is to keep Manaea up for the long haul.
"I think once you bring up a guy up like that, you're looking at more for the long haul," Melvin said. "We think he's ready to go. You make your reps here in the big leagues based on performance, but he wouldn't be coming here if we didn't think he had the ability to stay here for a while."
Utility man Matt McBride, who was called up by the A's on Wednesday, has caught Manaea once in Triple-A and said that so far, the prospect has lived up to the hype.
"His fastball -- he pounds the zone," McBride said. "His heater's got life on it, and he's just been attacking guys. … When he needed to, he mixes it up, locates the secondary stuff. He looked good."
Fantasy spin | Fred Zinkie (@FredZinkieMLB) Manaea deserves immediate attention from mixed-league owners. The left-hander has excelled as a Minor Leaguer (2.82 ERA and a 10.8 K/9 rate), and this season he's logged a 1.50 ERA across three Triple-A starts. Likely to make his big league debut at his pitcher-friendly home park vs. a strikeout-prone Astros lineup on Friday, Manaea can go straight into the active lineup in deep formats. Meanwhile, owners in shallow leagues can give the 24-year-old a bench spot until he proves that he can succeed in the Majors.
Chris Vannini is a contributor to MLB.com based in Detroit.