Carlos Correa’s two-run walk-off single Tuesday night against the Angels not only gave the Astros their fourth consecutive win, but it also brought their season record up to .500 for the first time since the second day of the season. Houston got off to an awful start to 2016, falling seven games out of first place before the end of April and not winning consecutive games until early May. Over the last six weeks, however, the Astros have reclaimed their place as one of the best teams in baseball and appear poised to reestablish their status as a contender.

Since May 1, the Astros have gone 29–19 for a .604 winning percentage, third-best in the American League over that span (behind Texas and Cleveland) and fifth best in the majors (adding the Giants and Cubs). If Houston continues at that pace, it will finish the season with 90 wins despite a brutal 7–17 start.

It might be a stretch to expect the Astros to continue to play better than .600 ball over the 100 games remaining in the season, but it’s not a stretch to believe that they have left their April woes behind them and will contend the rest of the way. Houston has already leapfrogged the White Sox in the wild-card race and stands just three games out of a postseason spot. Of the four teams between the Astros and that playoff position, they trail two of them, Seattle and Detroit, by just a half game in the standings. With another win against the Angels on Wednesday night, they’d be guaranteed to pass one of them, as the Mariners are currently in Detroit for a four-game set.

Slipping past the Mariners would put Houston in second place in the AL West, but that doesn’t mean that the division title would necessarily be within reach. The Astros are currently ten games behind the first-place Rangers, and worse yet, they have gone a mere 1–9 against Texas in head-to-head matchups this season, with the Rangers responsible for nearly a third of the Astros’ losses since May 1. Still, the wild-card race is wide open, and the Astros, though having only now reached .500, are already in the thick of it.

As for what has powered the Astros' turnaround, the improvement has been widespread, but the most dramatic change has come in their run prevention. The Astros allowed 5.1 runs per game in April but have held opponents to 3.8 since. Leading that charge has been the performance of their bullpen. Since May 1, Houston's relief corps has led the majors with a 2.50 ERA, 5.24 strikeout-to-walk ratio and 0.6 home runs per nine innings. Over that span, only the Yankees' relievers have struck out a higher percentage of their batters faced, and no other bullpen has issued walks or allowed base runners at a lower rate.

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The bullpen was crucial to the Astros’ success last year as well, and that was a strength they sought to reinforce in the off-season, ultimately landing 25-year-old closer Ken Giles from the Phillies in the seven-player trade that sent Vince Velasquez to Philadelphia. Giles has been a disappointment this year, losing the closer job in camp to veteran incumbent Luke Gregerson and proving homer prone in April, posting a 9.00 ERA on the month. Since May 1, however, he has allowed just one home run and struck out 27 men against six walks in 20 innings of work, stranding five of his six inherited runners. Giles’s 3.60 ERA over that span still isn’t what the team would like to see from him, and he has struggled a bit more of late, but he’s no longer pouring gasoline on the fire like he was in April, and his inflated batting average on balls in play suggests that further positive correction is to come.

That the Astros didn’t feel the need to keep Giles in the closer role after his poor spring is evidence of the flexibility that has allowed them to see such a marked improvement in their bullpen over the last two months. Gregerson, who saved 31 games for Houston last year, struggled himself and lost the job in early June. Since returning to the setup role in which he excelled prior to last season, he has yet to allow a run, inherited or otherwise.

With Giles and Gregerson demoted, the Astros have been able to move their most effective reliever into the closer’s job: Will Harris, who has allowed just two runs all season and leads the bullpen with a 0.57 ERA, 5.33 strikeout-to-walk ratio and 1.67 FIP. Harris, who was claimed off waivers from the Diamondbacks in November 2014, now has a 1.49 ERA in 102 2/3 regular-season innings for Houston over the last two seasons and has converted all five of his save chances since taking over as closer on June 5.

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Another Astro who has ascended to higher leverage work is rookie Michael Feliz, who bounced between Triple A and the majors during the first month of the season but has posted a 1.03 ERA in 26 1/3 innings with 36 strikeouts against four walks and just one home run allowed since the start of May. A 22-year-old converted starter who has pitched more than one inning in 10 of his 19 appearances this season, Feliz complements his upper-90s fastball with both a slider and a changeup and has been increasingly used as a setup man this month, getting more than three outs in the sixth inning or later in three of his last six appearances.

The Astros have also gotten valuable extended outings from 25-year-old rookie Chris Devenski, who has posted a 0.61 ERA in 29 2/3 innings of relief this season and averaged 2.5 innings per appearance. Devenski has been hit-lucky as a reliever, as you might expect (.222 BABIP), but he also has excellent peripherals (a 5.40 strikeout-to-walk ratio and just one home run allowed), suggesting that when the correction comes, it won’t be that dramatic.

Also valuable in relief has been deposed starter Scott Feldman, who was bounced from the rotation in late April. Since moving to the bullpen, Feldman has posted a 2.18 ERA with 19 strikeouts against just one walk in 20 2/3 innings. He has proven especially valuable in extra-inning contests, contributing six scoreless innings after the ninth in four extra-inning contests, all Houston wins.

With a nine-man bullpen and Feliz, Devenski and Feldman consuming all of those extra outs and innings, Houston's relievers have been able not only to carry a heavy load—only the A’s and Twins have received more innings from their relievers among AL teams this season—but also make a more significant contribution as the rotation continues to scuffle.

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That’s not to say that the rotation hasn’t improved, as well. Since May 1, Astros starting pitchers have combined for a 4.15 ERA, down from 5.10 in April. Still, with the exception of off-season addition Doug Fister—who has been hit lucky to the tune of a .236 BABIP over his last dozen starts, 11 of them quality—there have been no exceptional performances from the starting five.

Lance McCullers’s return has helped—he has a 3.53 ERA over his last six starts—but he has walked 5.8 men per nine innings over that span and averaged fewer than six innings per start as a result. Dallas Keuchel has shown improvement, adding some velocity and dramatically improving his control, going from 4.0 walks per nine innings and a 1.88 strikeout-to-walk ratio in in his first nine starts to just four walks in 38 1/3 innings over his last six starts against 40 strikeouts. His results are still lagging, however, with a 4.18 ERA in his last five starts, only three of which were quality. Meanwhile, pitching prospect Joe Musgrove has struggled in his last three starts in Triple A (0–3, 9.00 ERA), muting expectations that he might serve as an in-season upgrade for the rotation.

That all suggests that there’s continued room for improvement, as there is on offense, where George Springer has cooled off from his hot May and Jake Marisnick has not proven to be a sufficient platoon partner for Colby Rasmus, who has been struggling against lefties. Still, Jose Altuve continues to deliver an MVP-level performance; Carlos Gomez has hit .296/.368/.475 since returning from the disabled list on May 31; Luis Valbuena has hit .333/.348/.605 since May 24; and Correa’s walk-off hit on Tuesday was just the latest example of his hot hitting, as he has a .324/.446/.618 line since May 29.

Even if the Astros don’t play .600 ball for the remainder of the season, they could still fall short of 90 wins and make the playoffs. They did it last year, edging the Angels for the second wild-card spot with 86 wins. In 2014, 88 wins was enough to claim that spot in the AL. With the teams in the crowded East and Central divisions beating up on each other, there’s ample room for a team in the West—which boasts two of the three worst teams in the league in the Angels and A’s—to keep pace. That the Astros could overcome an April as awful as theirs was as quickly as they have is a reminder of just how good this team can be—or, better yet, how good they are.