"Guess all you want," Yost said.
In four spring outings, Villanueva has a 2.25 ERA. The 23-year-old posted a 3.69 ERA in 10 games with Milwaukee last season.
The Brewers are down to 15 pitchers in camp and have yet to decide whether they will carry an 11- or 12-man staff into the season.
Still nixed: Yost conceded Sunday what had become obvious: Outfielder Laynce Nix probably will have to start the season on the disabled list.
Nix suffered a strained right oblique muscle on March 12 during his final at-bat against the Rangers at Maryvale Baseball Park. He took some swings off a tee on Saturday, but he said he still felt sore.
Nix came to camp trying to win a roster spot. His injury could not have come at a worse time.
"But it wouldn't do me any good to rush back, either," Nix said. "You don't want to risk this becoming something that hurts you in the [regular] season. It's hard to predict what's going to happen, whether we're talking about a week, two weeks."
The Brewers acquired Nix last July 28, along with closer Francisco Cordero and outfielder Kevin Mench and a Minor Leaguer for outfielders Carlos Lee and Nelson Cruz. Nix hit .412 at Triple-A Nashville and earned a promotion, then batted .229 in 10 games with the Brewers. He was shut down with a painful foot injury that required surgery.
Extra work: Suppan got little help from his defense on Sunday, one reason he became the first Brewers hurler to throw 100 pitches this year. Suppan was approaching the century mark with two outs in the sixth inning and lobbied to stay in the game to face Tony Pena, Jr. But when Pena walked, Yost called for relief.
"It's a good building thing, and Soup is an experienced guy, but at this part of the [spring] when fatigue sets in, you really have to trust your mechanics," pitching coach Mike Maddux said. "It's a good building tool and a good little reminder of what we need to do."
Back to basics: Ben Sheets got a scolding a couple of weeks ago when he skipped a morning bunting session. Sheets was scheduled to pitch later in the day against the Giants.
But that was no excuse. Yost is taking fundamentals extremely seriously this spring.
"I don't want them to just be pitchers. I want them to be baseball players," Yost said. "I want them to be able to swing the bat, be able to bunt, be able to hit and run and slash, be able to field your position, be able to execute a pickoff with perfect timing."
Nick Leyva, a newcomer to Yost's coaching staff, plays a simulated game each day with the pitchers, complete with signs from the third-base coaching box. And two days a week, Brewers starters report to Leyva for individual batting instruction.
Running wild: The Brewers' new baserunning coach predicted Sunday that Rickie Weeks and Corey Hart will not be the only Brewers with double-digit stolen base totals this season. Prince Fielder and Bill Hall, the likely Nos. 3-4 hitters, could get there, too.
"I see those guys in the double digits, especially Billy -- easily," Ed Sedar said. "And Prince is always asking me at first [base], 'Can I do it?' I say, 'Go!' It's going to be fun to watch."
Sedar said he is encouraged by the team's baserunning this spring. The team is short on speedsters, but has focused on smart baserunning.
"At the Minor League level, you tell guys to do something and they're maybe a little hesitant," Sedar said. "Here, it's like, 'Boom, let's do it.' Everything we've mentioned, these men have been able to go out there and get it done -- and it's fun to watch."
On deck: Many of the regulars will enjoy a full day off when the Brewers make their final trek down to Tucson on Monday to face the Diamondbacks. Arizona's Enrique Gonzalez is scheduled to start against Milwaukee right-hander Claudio Vargas. Brian Shouse, Jose Capellan, Joe Thatcher and Derrick Turnbow also are on the list for the Brewers. Those Brewers getting a rest include Brady Clark, Craig Counsell, Johnny Estrada, Fielder, Hall, Geoff Jenkins, Kevin Mench and Mike Rivera. Wise is scheduled to work an inning in Minor League camp.