PHOENIX -- The data was so surprising they double-checked it Monday morning, and yes, Statcast™ still said 21-year-old Brewers right-hander Freddy Peralta threw four-seam fastballs for 90 of his 98 pitches of Sunday's sparkling, 13-strikeout Major League debut at Coors Field.

Actually, Peralta said a day later, one of those fastballs was a changeup.

Details, details. While Statcast™ learns the rookie's repertoire, the bigger question remained: How does a rookie dominate a Major League game with essentially a single pitch?

With two varieties of that pitch -- one of which behaves like a cutter.

"It's a different grip, and I throw it and the ball just goes," Peralta said. "It's the same speed; 92, 93, 94 [mph]. I threw a lot of fastballs, yeah. A lot. They couldn't hit the fastball yesterday."

Said Christian Yelich, who had a clear view from center field, "It looked like it was moving five feet."

The result was one of the best starting debuts in Major League history, and a Brewers rookie record for strikeouts in a game. Peralta's 13 strikeouts were fourth-most in a Major League debut since 1893, and the most since Stephen Strasburg struck out 14 Pirates in 2010.

"I just called fastball," said catcher Manny Pina. "If it was a straight fastball, he can't do that."

Pina had an intriguing theory about that movement: The baseball had something to do with it. Generally speaking, pitchers say Major League baseballs "ride" more than their Minor League counterparts, and pitches ride when they are thrown with elite spin rate. Peralta had that, according to Statcast™. Of 157 starters who had thrown at least 50 four-seam fastballs through Sunday, Peralta ranked 10th with an average spin rate of 2,451 revolutions per minute. The list, led by Justin Verlander (2,620 rpm), is stocked with pitchers who live at the top of the strike zone.

The Rockies tallied only one hit -- a David Dahl single with one out in the sixth inning on the lone changeup Peralta threw. He also threw eight curveballs, a new pitch this season that replaced his slider at the suggestion of Brewers pitching coach Derek Johnson.

Johnson taught Peralta the curveball grip this spring in Peralta's first big league camp.

"He told me, 'I think that you can have a very good curveball because of how you are throwing and how your fastball works. You have a chance to have a very good curveball. You can try it,'" Peralta said. "I said, 'OK, let's do it.' I threw a bullpen [session] that day and the curveball was nice."

He's been working on it since. Peralta was not throwing any sliders in Triple-A, where he rode that fastball to a Pacific Coast League-leading 46 strikeouts in 34 2/3 innings.

But those secondary pitches remain very secondary for Peralta, who will fire fastballs at the Twins in his next scheduled start on Saturday.

Can he succeed in the long term if he remains reliant on that one pitch?

"Look, Freddy performed great [Sunday]," Brewers manager Craig Counsell said. "As he grows, he's always going to be looking for ways to get better, and different ways to get hitters out. I think what was clear is that he has a very special pitch. There were several balls thrown in the middle of the strike zone that were swings and misses, which does not happen much in Major League Baseball.

"So, rather than say, 'Is that sustainable?' I would say Freddy has a really good foundation and a really special pitch that hitters don't like. It's a great place to build off of."

Braun scratched

Ryan Braun, a day removed from the second four-strikeout game of a career that spans 1,595 Major League games, was a late scratch Monday night against the D-backs with right mid-back tightness. It is an ailment that has plagued Braun occasionally in recent seasons.

Hernan Perez moved from second base to Braun's spot in left field in the amended lineup as the Brewers stuck with the original plan of a day off for Yelich.

Last call

• Chase Anderson was feeling significantly better Sunday after missing Saturday's start with a stomach ailment, and was in even better shape by Monday afternoon. The Brewers opted for a backdated stint on the 10-day disabled list after Anderson fell ill, so he won't be eligible to start again until May 21 at Miller Park against the D-backs. At the moment, that is when Anderson is expected to return to action.

"That's not set in stone, but that's what we're headed towards," Counsell said.

• Another Brewers starter on the DL, Zach Davies, who has been sidelined by right rotator cuff irritation, felt fatigued but not overly sore after back-to-back days of playing catch Saturday and Sunday. Barring a setback, he will try to throw a bullpen session on Wednesday in Arizona. A return date is not set for Davies.

• First baseman Eric Thames caught up with teammates during batting practice Monday for the first time since departing for left thumb surgery. The swelling in the thumb has improved, but Thames remains in the therapy stage of his rehab in Phoenix.

• The Brewers will take reporters and broadcasters on a tour of the Maryvale Baseball Park renovation site on Tuesday. Look for a story and video on Brewers.com late in the day with progress at the team's Spring Training home.