But the Brewers' other four starters are new to Estrada, except for the few times he's faced them (he has 47 career at-bats against pitchers on Milwaukee's 40-man roster). Over the next six weeks, Estrada will work on and off the field to catch up.
"I like to get inside a pitcher's head so I know what they're thinking at certain times. That makes my job easier," Estrada said. "A lot of that comes from talking to them off the field. If you don't talk off the field, you would see a bad product on the field -- a lot of shaking off and confusion."
The 30-year-old Estrada would have had a salary-arbitration hearing on Friday had he not agreed to a one-year, $3.4 million contract on Feb. 2. He can trigger a $50,000 incentive clause by either starting 125 games or accumulating 500 plate appearances.
Estrada talked at length again on Saturday about keeping a quick tempo, but this time he did not mention Vargas, a generally slow worker. Estrada got his first action in a Brewers uniform on Friday, when he caught a handful of bullpen sessions.
"I saw some things I liked and some things I didn't like, but I didn't voice my opinion out loud," Estrada said. "I don't want to come in and start talking people's heads off right out of the gate. Some guys are going to be rusty at this point."
Estrada and others have been working out at Maryvale Baseball Park for the past several days, but Saturday's arrivals included pitcher Jeff Suppan and outfielder Bill Hall, two of the team's highest-paid players. Suppan will make his unofficial Brewers debut on Sunday afternoon, when manager Ned Yost will hold his first formal practice of the year.
Early surprise: It's way too early to predict a breakout, but Estrada singled out right-handed newcomer Grant Balfour as a player to watch this spring. The Brewers claimed Balfour off waivers from the Reds, and he will compete for a bullpen spot.
"He was my first bullpen [session] of the year, and he was unbelievable," Estrada said. "His stuff is sharp. I didn't expect that."
Balfour, a native of Australia, underwent Tommy John elbow reconstruction surgery in 2005, and later had tears in his labrum and rotator cuff repaired. He was limited to nine Minor League rehabilitation assignments.
He will have plenty of competition, though. Jose Capellan, Francisco Cordero, Brian Shouse, Derrick Turnbow and Matt Wise are locks to make the staff, and Aquino and Dennis Sarfate are also strong candidates.
Full strength: Laynce Nix, who will be part of the Brewers' fierce outfield competition this spring, also checked in on Saturday and said he is back to full strength after undergoing foot surgery last fall.
"I haven't had any setbacks at all," he said. "My main goal was to be able to come in here and run full speed. So far, it's going good."
Nix underwent surgery on his left big toe last Sept. 14 to repair a painful injury similar to turf toe. The Brewers acquired him along with Cordero and outfielder Kevin Mench from Texas in late July, and Nix was hoping to make a positive impression on his new organization. But the pain proved too much to tolerate.
The decision to opt for surgery in September was intended to leave Nix ready to compete in Spring Training. Things "came together" in January, and he spent the entire last week working out at Maryvale.
Hall is expected to start in center field, and Corey Hart, Geoff Jenkins and Mench are expected to see significant playing time. That leaves players like Brady Clark, Gabe Gross and Nix in a battle for backup spots.
What does Nix think of the competition?
"It doesn't matter what I think," he said. "Everybody is going to work hard, and we'll see how things pan out at the end of spring."
Signings: On Thursday, the Brewers announced another round of signings, a formality of the spring. Catcher Mike Rivera, utilityman Vinny Rottino and right-handers Ben Hendrickson and Marino Salas agreed to terms on one-year deals.