The Astros were already World Series favorites. Then they added Zack Greinke

Three headlining starting pitchers were dealt before this year’s trade deadline. Two of the three went to fourth-place teams, but the other was swooped up by the Houston Astros, the best team in the American League.

Zack Greinke joins a staff that already includes Justin Verlander and Gerrit Cole, which will make them the favorite in just about any October series.

Astros starters already lead MLB in strikeouts (709) and strikeout rate (28.4 percent). They rank fourth in ERA (3.75), sixth in FIP (4.08), and sixth in walk rate (6.9 percent). Greinke has the third-best walk rate in baseball (3.7%) and the fourth-best strikeout-to-walk ratio (6.43), do go with his 2.90 ERA in 23 starts.

Houston’s rotation is a juggernaut.

Wade Miley, with a 3.06 ERA in 22 starts this season, is now the fourth starter in Houston. The Astros starting staff now includes four of the top 13 ERAs in baseball.

The Astros own an eight-game lead in the American League West, on pace for 103 wins after back-to-back 100-plus-win seasons and a championship in 2017. Houston is a World Series favorite, at 3.65/1 odds to win the Fall Classic per Bovada. They have a 99.9-percent chance to make the postseason per both Baseball Prospectus and FanGraphs.

Greinke wasn’t acquired to get the Astros to October, he is on board to help them win in October. Plus, the psychological boost of adding a great player is immense.

“The energy in our room after a thing like that happens is palpable,” manager A.J. Hinch told reporters Wednesday. “You know that what you have in front of you is one of the greatest opportunities to keep the winning ways alive.”

“There was some hooting and hollering,” said Gerrit Cole, Greinke’s new rotation mate.

Anything that spurs hooting and hollering has to be good, right?

The easy comp here for the Greinke acquisition is when Houston nabbed Justin Verlander two years ago. Both are former Cy Young Award winners and likely future Hall of Famers, in their mid-30s when traded to the Astros. Verlander had about $60 million and two more years left on his contract when acquired by Houston, with the Tigers kicking in just over $17 million as part of the deal. Greinke has about $74 million and two more years left on his deal, with the Diamondbacks kicking in $26 million.

Verlander was acquired on Aug. 31, 2017, when teams could still trade players after July 31 though they were subject to waivers. Now, with only a single trade deadline starting in 2019, this time the Astros got their man sooner rather than later.

Verlander is the comp preferred by Astros fans because it led to a World Series win, the first in franchise history. A championship justifies every prior act, and changes the lens with which we view moves that led up to it.

But in reality no move can guarantee a World Series championship. The October landscape is much too treacherous.

What if we look at the Phillies of nearly a decade ago as a comp for the Greinke trade instead? Those Philadelphia teams were juggernauts, too, and after back-to-back World Series appearances and a championship in 2008-09, the Phillies acquired Roy Halladay, at the time the best starter in baseball. They also traded away Cliff Lee, but the Phillies rotation was incredible in 2010, and at the deadline they added another ace in his 30s, Roy Oswalt.

Philadelphia was the clear favorite to win the World Series that year and won 97 games, but lost in the NLCS. Then they added Lee back to the rotation for 2011 and won 102 games, but lost in the first round. Baseball can be cruel sometimes. Even if you are stacked with aces, your season can be royally flushed at any moment.

Greinke certainly makes an already great team better, and the Astros are the clear favorites to win the World Series. But there are no guarantees in baseball.