This wasn’t supposed to happen. Not this soon. Not this season.

The 2013 Astros were supposed to be horrible. The worst team in Major League Baseball. Potentially one of the saddest, sorriest clubs in the history of a sport defined by tradition and, at best, colored by integrity and respect.

The Astros have 105 games to fulfill the lowest of expectations and bring a crooked, nasty smile to the faces of analysts, baseball insiders and media who want to see an experiment fail.

But since May 15, a young, unproven club with a $21 million active payroll — by far the lowest in MLB — is 10-7. And during the Astros’ last five games, first-year manager Bo Porter has guided MLB’s hottest team.

The resilient, gutsy Astros won again Sunday, fighting off the lethargic Los Angeles Angels and claiming a 5-4 victory during an American League West matchup at Angel Stadium.

“I’m extremely proud of the entire organization,” Porter said. “I’m proud of not only the guys in that room there — the 25 guys that we have — I’m proud of our coaching staff.

“Overall, we all looked at these guys and said, ‘You know what? We have a group of guys that can play.’ These guys enjoy playing together. They’ve got grit. They come to the ballpark each and every day with an attitude that we’ve got a chance to win this ballgame.”

Extending their season-high winning streak to five, the Astros (20-37) took the series from the Angels (25-32) and are 6-3 against a star-laden Los Angeles team that features a $148 million payroll.

The Astros have won six of their last seven games and three of their last four series.

The youngest club in baseball posts an average age of 27, has no widely recognizable players and is expected to be a heavy seller at the trade deadline, continuing to ship veterans and mid-level talent to stock its steadily improving farm system.