But Greinke, the ace with the six-year, $206.5 million contract, was the choice.
"He's been our horse all year long," D-backs manager Torey Lovullo said. "He's won 17 games. He's paced us on days where we needed somebody to pitch a big game. He's allowed other guys to step up into different roles behind. He's been everything that we needed all year long. I don't think that's going to change in one game. I know he's going to be ready for [tonight]."
After a lackluster first season in Arizona last year, Greinke has rebounded in 2017 in large part because of his ability to get batters to chase pitches on the corner and slightly low and away off the corner, per data from Statcast™.
Heading into Sunday's season finale, Greinke ranked sixth in baseball in chase rate at 33.16 percent. When it comes to most strikeouts outside the zone, Greinke is fourth in the Majors as of Sunday with 131.
Arizona catcher Chris Iannetta points to Greinke's ability to throw four pitches -- fastball, curve, change, slider -- for strikes when he needs to, which allows him then to expand the zone on the corner.
"It's his execution and his ability to execute four pitches at any time," Iannetta said. "That's what makes him one of the best pitchers in the game."
Greinke has faced the Rockies five times this year, compiling a 2-1 record and a 3.41 ERA, so there is familiarity on both sides.
That can work against a pitcher a lot of times, but that lessens when facing a hurler with four pitches.
"I just think when you have a guy that can execute the way he does and can throw four pitches for a strikes the way he does, the quality of his pitches, it would be tough for anybody," Iannetta said.
Greinke's experience no doubt played a role in his selection to start the game. He is the only member of the starting rotation who has seen postseason action.
While this will be Greinke's first Wild Card Game appearance, he has made nine postseason starts and is 3-3 with a 3.55 ERA.
Greinke has also been almost unbeatable at Chase Field, going 13-1 with a 2.87 ERA in 18 starts there this year.
"There's about 35 reasons why we believe in Zack," Lovullo said. "We know he's going to go out there with a great game plan, be able to make adjustments, attack that game plan and be ready to hand it off to the next guy in the bullpen."