What's the Astros' formula for early-season success?

On Sunday, the Houston Astros did it again while beating the Detroit Tigers 10-8 to split a four-game series. What’s "it"? It’s the Astros falling behind early, but coming back to win with their league-leading power while their bullpen and defense combine to stifle the opposition.

After the Astros put a quick three-spot on the board to start Sunday’s game against Anibal Sanchez, the Tigers answered with a five-spot against Roberto Hernandez. That really wasn’t that much of a surprise -- Hernandez’s 2015 FIP (fielding independent pitching) was 4.95 coming into the game, and it was 4.85 last year with the Los Angeles Dodgers. That’s who Hernandez is, a fairly typical No. 5 starter, and even with Sanchez struggling this season, he came in boasting a career 2.96 FIP as a Tiger. Per ESPN Stats & Information research, over the past five years teams that score five or more runs in the first inning win 86 percent of the time (155-24).

In another year, it would seem obvious how this was supposed to turn out: The Tigers would proceed to beat Hernandez into the ground, pad their stats against the relievers who pitch when their team isn’t leading, and call it a good day in the Motor City.

Maybe that was last year against the Astros, or even the past several. No longer. The Astros scored seven runs to catch up and win, four on a pair of home runs in the sixth inning off a tiring Sanchez.

That reflects something of a season-long trend for the Astros. Counting Sunday, they have been outscored through the first five innings of their games by a combined score of 111-96. That’s despite out-homering their opponents 33-23.

But how about in the sixth through ninth innings, where you face bullpens and scoring gets harder (MLB relievers are allowing a collective 3.9 runs per nine this year, against starters’ 4.4 RA/9)? In the back four, the Astros lay into teams. They’ve scored more total runs in 50 fewer innings at-bat, plating 98 men and homering 30 times, while their opponents have scored just 46 runs and hit 12 homers in that time. Much of that is the benefit of getting above-average power from every lineup slot but center field, but even there Jake Marisnick is providing good offense.

By winning after trailing 7-3 through five, the Astros came back from four runs down to win for the first time in more than a year. The last time was May 14, 2014, against the Texas Rangers, and they’d lost 40 straight games in which they’d been in that situation. (Thanks again, ESPN Stats & Info.)

That makes this win unusual, but again symptomatic of the other half of what’s becoming a team-level formula for success: A revamped bullpen that keeps the Astros in games. Astros relievers have a collective 2.14 ERA, a mark second only to the Royals’ much more famous relief corps in the American League. They can thank the offseason additions of veterans Luke Gregerson, Pat Neshek and lefty Joe Thatcher, as well as the decision to grab Will Harris on waivers from the Diamondbacks.

Gregerson gives the Astros a workmanlike closer, while Neshek and Thatcher are a pair of premium situational relievers for late-game matchup battles. Harris has been especially remarkable as the guy coming into games the Astros narrowly trail late, striking out 29 in 22 2/3 IP, allowing just 12 baserunners and a run. Adding that quartet to Tony Sipp and Chad Qualls, and you’ve got a strong bullpen. The net cost? Just $13 million on the Astros’ 2015 payroll, a worthwhile investment to put a difference-making everyday unit on the field.

You can add all of that to an improved defense. As noted on Saturday, the Astros are fielding an improved defense, one that has seen its defensive efficiency improve from .702 in 2014 to .719 in 2015.

So if the Astros are with you through five, they have the bullpen to stay in a game, and the top-to-bottom power in their lineup to kill a mistake if you can’t keep up in the matchup game. This was a game and a series in which these elements of the Astros’ early-season success came together, and where splitting with the Tigers doesn’t seem so extraordinary because good teams do that.

League-best power, quality relief pitching and a bit of defense? Put those things together and what the Astros have in any ballgame is a puncher’s chance, not just the days when Dallas Keuchel dominates. And because those building blocks for success rely on multiple players and not just one star, the Astros might have the assets to turn their 29-16 start into success they can carry to the second half and beyond.

Christina Kahrl writes about MLB for ESPN. You can follow her on Twitter.