SEATTLE -- The Astros are the hottest team in the Majors since, well, the Astros.

Not since Houston’s own 12-game winning streak last June has any club won as many regular-season games in a row as the Astros’ current run, which reached nine straight victories after Sunday’s 3-2 win over the Mariners.

They’ve come from behind, outslugged and outpitched everyone in their path over the past week and a half, with contributions from an eclectic cast of characters.

Here are four reasons why Houston remains the hottest team in baseball.

1) Contributions up and down the lineup
The Astros’ hero on Sunday was backup infielder Aledmys Díaz, who was hitting seventh. On the day that second baseman Jose Altuve snapped his homer streak of five games, Diaz led off the seventh with a solo shot that broke a 2-2 tie and gave Houston the cushion it needed to turn the game over to the bullpen.

Diaz, who the club acquired to fill a void of defensive versatility that Marwin Gonzalez had given them before he left via free agency, hadn’t played since Wednesday, and he’s faced an admitted challenge adjusting to a non-everyday role. But he’s now homered twice in 23 plate appearances this year.

“You see a lot of stars on this team, but everybody is humble,” Diaz said. “Everybody tries to push for the win. This is a great experience for me. I like being in this clubhouse.”

Diaz’s performance on Sunday is a reflection of the entire offense during this win streak. Leadoff man George Springer snapped his 15-game on-base streak, but in congruence, Michael Brantley extended his on-base streak to eight games, during which he’s hitting .394 -- including a 2-for-4 showing on Sunday when he lined a critical two-run single in the sixth that chased Marco Gonzales, who had given up just one hit through five innings.

“It’s a special team, but we knew that going into the season,” Brantley said. “That’s the approach that they had before I even got here. I just wanted to join in and do whatever I could to help out.”

The Astros also have the depth to account for minor stings, such as Alex Bregman’s right hamstring injury earlier this week that forced the All-Star third baseman to miss two games. Houston moved Yuli Gurriel from first to third and installed a combination of Diaz and Tyler White at first. Bregman is 1-for-7 since returning to the lineup on Saturday, yet he leads the team with a .414 on-base percentage.

“It’s a different guy every night,” Bregman added. “It’s fun to be a part of. Most teams, [Diaz] isn’t lower in the lineup. Right now, our one through nine, everybody is just trying to put together a good at-bat. We string together well.”

2) Altuve, Correa are healthy -- and the numbers back it up
Speaking of health, the Astros’ MVP-caliber middle infield of Altuve and shortstop Carlos Correa, who were mightily limited by their respective injuries throughout last year’s postseason, are back at full strength. And it’s showing in their defensive athleticism and numbers at the plate.

Even though he insists that it’s not intentional and instead a byproduct of hunting optimum pitches, Altuve on Saturday became just the ninth second baseman in history to homer in five straight games, a feat many within Houston’s clubhouse call remarkable given that Altuve is six months removed from right knee surgery.

“I don't think anyone really can put into words or can appreciate what he was going through last year at the end of the season,” manager AJ Hinch said. “He put in a lot of work and was very diligent. It took a lot more rehab than I think anybody imagined.”

Altuve is slashing .328/.371/.688, and Correa has put up a line of .313/.400/.542. Correa’s exit-velocity readings are also back in line with the elite level he was at before suffering a back injury, an encouraging signal that his success is sustainable.

“Last year, it was impossible to get healthy,” Correa said. “This year, so far, it's been the real me and being healthy, which is the most important thing.”

3) The pitching staff picks each other up
Houston starter Gerrit Cole overcame a leadoff homer to Mitch Haniger and consecutive doubles in the third to Haniger and Domingo Santana to strike out 11, which matched Justin Verlander’s total on Saturday. During their win streak, Astros starters have limited opponents to a .618 OPS, second best among teams that don’t use an opener, while racking up 56 punchouts, tied for fourth most.

Cole, Verlander and Collin McHugh each turned in their best start of 2019 this past time through the rotation, but Wade Miley labored through just four innings on Friday due to a 41-pitch first inning, which forced Houston to turn to its bullpen early.

Yet with two off-days during their 10-day road trip, including Monday, Houston has the luxury to move Brad Peacock to a long-relief role and go with a four-man rotation. Peacock struck out seven over 3 1/3 innings on Friday, which positioned Roberto Osuna for the first of three straight saves in Seattle.

Osuna now has seven saves in as many attempts, and setup men Will Harris and Ryan Pressly have yet to allow a run in a combined 12 innings.

“They're nasty,” Cole said. “Our whole bullpen is really good. We've got a lot of guys that will take the ball multiple days in a row, give you their best effort. They're not afraid to pitch in leverage or clean up your mess.”

“Best in the game. Not even close,” Bregman said.

4) The Astros insist that they’re over last October
Houston’s win streak has come via sweeps of the A’s (who won 97 games and reached the postseason last year), the Yankees (who won 100 and also played into October) and the Mariners (who entered this weekend 13-2 and leading MLB in just about every offensive category).

Last year’s sudden postseason exit didn’t stir the Astros to prove that they were better than their five-game American League Championship Series defeat to the Red Sox, they say, but instead say their scorching-hot streak is reflective of a professional and consistent day-to-day approach.

“This sounds maybe a little aggressive, but we’re a good team,” Hinch said. “And we win. And we’ve got to keep working to do better in other aspects of the game, but we’re not trying to make up for last season. We don’t give two [cares] about last season.”