Jackie Bradley Jr., Boston’s grand slam hero, is about to get wet, courtesy of Mookie Betts after the game. (Thomas Shea/USA Today Sports)

The Houston Astros had put themselves through something close to organizational hell to get to the point where they could hand the ball to Roberto Osuna in the late innings of a one-run game in October. They saw their clubhouse cleaved, at least initially, by the controversial trade that brought him to Houston in July. They were blasted by the national media. They endured merciless treatment from fans on the road. But in their own calculation, it would all be worth it if Osuna delivered the biggest outs in October’s biggest moments.

What happened Tuesday night at Minute Maid Park with Osuna on the mound, then, will be seen by some as karma, by some as a giant choke-job in a high-pressure situation and by fans of the Boston Red Sox as one more sign their team — the best in baseball all season, if not a decade or more — is on its way to baseball’s ultimate prize a couple of weeks down the road.

Had Boston’s 8-2 victory in Game 3 of the American League Championship Series pivoted on any other inning than the one Osuna started, it would have been a neat and tidy example of a tight game broken open in the top of the eighth with one mammoth swing of the bat — that being Jackie Bradley Jr.’s towering drive to right field for a grand slam.

“It’s huge,” Bradley said. “Runs are at a premium. We never feel like [a few runs are] going to be enough.”

But because Bradley’s blast came off Osuna, and because Osuna was acquired from the Toronto Blue Jays while still serving a 75-game suspension for an alleged domestic violence incident, and because the Astros made that trade knowing full well there was only one outcome in which it would be deemed a success — and this outcome wasn’t that — that eighth-inning collapse, should the Astros bow out in this series, could come to define their season. As it stands, they trail the best-of-seven series two games to one, with Game 4 on Wednesday night.

Astros closer Roberto Osuna, who was charged with five runs in his appearance in Game 3, has to watch the Red Sox celebrate after Bradley’s slam. (Lynne Sladky/AP)

“That’s a pitch I always get him out with,” Osuna said of the 1-1 fastball Bradley hit for a grand slam. “He hit it today, but I will go there a hundred more times. It’s tough because we lost, and we don’t want to do this to the team, especially in a situation like that, but we’re ready to bounce back [Wednesday].”

During the game, a report by Metro Boston said Major League Baseball security had removed a person identified as an Astros employee from the area near the Red Sox dugout during Game 1 at Fenway Park three nights earlier, amid suspicions of sign-stealing. But a league source, while confirming the report, said the employee in question was determined to have been only trying to see into Boston’s dugout to make sure the Red Sox weren’t stealing Astros signs, as opposed to stealing Red Sox signs himself.

“We are aware of the matter, and it will be handled internally,” MLB’s chief communications officer, Pat Courtney, said Tuesday night, declining to elaborate.

The Red Sox said they believe the matter was limited to Game 1 and was not a concern Tuesday night, although they changed their pitch-calling signs frequently, even with no runners on base

“I’m always concerned about [it],” Manager Alex Cora said. “If we feel there’s something going on, we switch the signs.”

For Tuesday night’s game to wind its way to Bradley vs. Osuna in the eighth, much had to happen. The respective starters, Houston’s Dallas Keuchel and Boston’s Nathan Eovaldi, had to survive rocky beginnings to get the game to their bullpens in fine shape. The Astros had to make a series of fine defensive plays, with left fielder Tony Kemp saving at least one run with a leaping catch at the wall in the third and Alex Bregman making a series of dazzling plays at third base. Boston’s Steve Pearce had to homer in the sixth off Joe Smith to put the Red Sox ahead.

And Boston’s half of the eighth against Osuna, which began with No. 3 hitter J.D. Martinez flying out to the warning track in right, had to get all the way to Bradley, the No. 9 hitter. It did so thanks to a couple of softly hit singles, a forceout and consecutive two-out, two-strike hit-by-pitches, the second of which came with the bases loaded and forced in a run that made it 4-2. The stage was then set for Bradley, who, two nights earlier, had stroked a bases-loaded double that was the biggest hit in Boston’s Game 2 victory.

“[If] we get out of that [eighth inning] 3-2, we’ve got plenty of outs left,” Astros Manager A.J. Hinch said. “And you never know what can happen — as we saw.”

The Astros’ loss was just their second in 12 postseason games at Minute Maid Park since the start of last October, a stretch that saw them win the franchise’s first World Series title on the first night of November. The 43,102 fans who jammed into the stadium Tuesday night could have been forgiven for thinking they were there merely as witnesses to another step in a month-long coronation. If anything, this year’s Astros team appeared to be even better than last year’s champions.

A big part of that confidence stemmed from Osuna, the type of lock-down ninth-inning man they had to make do without a year ago. The Astros took great pains to assimilate him into their clubhouse, where some players were initially hesitant to embrace the move but understood they needed him to reach their goal.

As Osuna handed the ball to Hinch on the mound, five runs charged to his name, and headed toward the dugout, many in the crowd began to boo, and for the first time perhaps some questioned whether the Astros’ move had been worth it. But this was no time for the Astros to ponder the bigger questions. They were two losses from elimination, three wins from another trip to the World Series, and another game was less than 24 hours away.

“I told him on the mound [that] there’s going to be some big outs we’ll need from him in the rest of the series,” Hinch said. “He’ll clear his mind. Closers have a short memory, especially him. We’re going to expect him to close out [Wednesday] night’s game with the lead.”