BALTIMORE — The Houston Astros have mastered the art of the high-impact midseason trade. In 2017 they got Justin Verlander, an ace who helped lead them to their first World Series title. Last season it was reliever Ryan Pressly, who has since become an All-Star. This summer they welcomed starters Zack Greinke and Aaron Sanchez, among others.

But in 2016, things were different. The Astros had won a wild-card berth the year before, but they were trailing for a playoff spot at the Aug. 1 non-waiver trading deadline. Their post-season deficit was just two and a half games, but Jeff Luhnow, their analytically-minded general manager, did not like his odds.

“We estimated on the day of the deadline our probability of making the playoffs around 25 percent,” Luhnow said. “And that wasn’t enough for us.”

Instead of adding, Luhnow subtracted a couple of middle relievers. He sent Scott Feldman to the Toronto Blue Jays for Lupe Chavez, a pitcher now in Class A. And he sent Josh Fields to the Los Angeles Dodgers for Yordan Alvarez, who since a call-up in June is off to one of the hottest starts in major league history.