Incorporating those two pitches alongside the fastball and changeup is making his already above-average pitches even harder to track.
"He's just becoming a more versatile pitcher and that makes him less predictable," Matheny said. "I think that's what takes a young pitcher to the next level."
Wacha's newest toy is the cutter, which he is throwing almost twice as frequently as he did in an abbreviated 2014 season. He had actually thrown a higher percentage of cutters (20) than changeups (17) in his first two starts, which impresses upon the pitch's growing reliability.
The fact that the cutter and changeup arrive at the plate at about the same velocity, but break different directions only makes the combo more confusing for an opponent to pick up.
"It keeps something in the back of their head that I might be throwing it," Wacha said of the cutter. "I've got confidence in every pitch, and I've had confidence in them. It's just about being able to throw them for strikes and then expanding the zone with those pitches as well. I'm just trying to keep them off balance."
He's showcasing an elevated fastball at times, too, with the 94-mph one he threw past Bryce Harper in the fifth perhaps his most critical of the day. Harper was one of three Nationals batters in that inning unable to drive in a runner from third.
As for the curveball, it's graduated from a just-trying-to-get-it-over pitch to one that can be an out pitch. Matheny, who watched Wacha throw several effective first-pitch curveballs Thursday, said he is going to encourage Wacha to further incorporate the improved offspeed pitch in put-away spots.
In running his record to 3-0, Wacha became just the fourth National League pitcher to win each of his first three starts. None of the others, however, had the head-to-head challenges that Wacha faced.
"Going against guys like Cueto, Scherzer, you know you're going to have to go out there and try to match zeros with those guys," Wacha said. "Once the game starts, you kind of forget who is on the other side and just attack hitters with your gameplan. It ended up being a pretty fun game today."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB and like her Facebook page Jenifer Langosch for Cardinals.com. This story was not subject to the approval of Major League Baseball or its clubs.