The only surprise is he is doing it on purpose.
The majors' second highest-paid pitcher this season - he's making $32 million -- never hesitates to tinker with his pitch selection, and that's been evident in recent games. Greinke is throwing a pitch that he's never flashed before, a slower-than-slow curveball that arrives at the plate with a speed that barely exceeds that of a knuckleball.
So, when the Miami Marlins take on Greinke (7-5, 3.66 ERA) and the Diamondbacks on Thursday in the final contest of a four-game series at Marlins Park, they will be facing one of the majors' most familiar pitchers yet one they've never quite seen before.
"It's been working really good this year," Greinke told reporters after he pitched six shutout innings in a 7-2 Diamondbacks victory Saturday in Pittsburgh. "I don't know how long it will last for, but it's been working good. I didn't throw any harder curves, where I think the whole year, I've kind of done both. But my harder one gets hit usually. So, I started throwing only the slow ones."
Greinke opposes Marlins right-hander Trevor Richards (2-4, 4.91), who has won two of his last three decisions. Richards won 6-2 at Colorado on Saturday, permitting one run and three hits over six innings, striking out eight and walking two.
The Diamondbacks could not have received a much better performance Wednesday from left-hander Robbie Ray as they beat Miami 2-1 and improved to 7-2 on their 10-game road trip. Ray, out since April 29 with an oblique injury, allowed two hits over six shutout innings while making 83 pitches.
Daniel Descalso hit a key pinch-hit homer for the Diamondbacks in the eighth inning to make it 2-0, and reliever Yoshihisa Hirano tied a club record by making his 24th consecutive scoreless relief outing, throwing a scoreless seventh inning.
Arizona overcame a shaky ninth inning from closer Brad Boxberger, who gave up a solo homer to Starlin Castro before allowing the potential tying run reach second with one out before retiring the final two batters.
"Other than that, we didn't get a lot going," Marlins manager Don Mattingly said. "Starlin Castro's always going to get his hits. Hopefully he can keep that rolling."
The Diamondbacks can win the four-game series if they take the Thursday matinee behind Greinke, whose velocity is down the last few seasons -- his four-seam fastball maxed out at 90.7 mph in Pittsburgh.
He once threw consistently in the mid-90s. But when he mixes in an eephus pitch-like curveball that doesn't even reach 68 mph, it makes his fastball look all that much harder. And he threw 12 of them against the Pirates.
Still, after Pirates rookie Austin Meadows barely missed homering on Greinke's final super-slow curveball of the day, the right-hander said, "It might have been running its course. So maybe 12 times was too many."
Whatever Greinke is throwing up there, it's working. He has won four of his last five decisions, and he's helping keep the streaky Diamondbacks in first place.
They began the season 24-11, then dropped 15 of 17 to fall to .500 at 26-26 but have since won 20 of 28 and six of seven.
Greinke has been especially tough on the Marlins during his career, going 6-0 with a 3.53 ERA against them in 11 games (10 starts). He last faced them June 2, limiting them to one run on seven hits in 6 2/3 innings, striking out six and walking one while earning the victory in a 6-2 Diamondbacks win. Castro hits him well, going 9-of-25 with a home run and four doubles.
The first-place Diamondbacks return home following the contest to begin a three-game weekend series against the NL West rival San Francisco Giants.