Just as new Cubs manager Rick Renteria did after he was formally introduced, Mueller reached out to the players, calling to say hello. Mueller got to work at the Mesa facility in December, and by the time Mueller and assistant hitting coach Mike Brumley arrived at the Cubs Convention earlier this month, they had watched video of everyone on the roster.
Cubs position players don't have to report to Spring Training until Feb. 18, but Mueller and Brumley aren't waiting. One of the early birds in Mesa was second baseman Darwin Barney.
"[Mueller] and Brumley work together very well," Barney said. "Their ideas are simple: 'Let's stabilize the base, let's release some tension and let's be the same every at-bat.' That's just a simple version of what they're trying to do with me. I really believe in it and I feel good moving forward. Hopefully things work out for our offense this year. I think it will."
The Cubs hope so, too. Barney, 28, is coming off a season in which he posted career lows in batting average (.208), on-base percentage (.266) and slugging percentage (.303). A National League Gold Glove Award winner in 2012, he was a finalist for the defensive award in 2013.
"I got to the big leagues with my offense, as most guys do," Barney said. "The defense came. You have to remember that this game is hard and you're not always going to play as well as you want. Unfortunately, nothing came together last year, and I'm very confident that's not going to happen again."
It's up to Mueller and Brumley to get the second baseman back on track. The early sessions have been a chance for the hitting coach to gain his new pupils' trust.
"It's a matter of getting these guys in the cage, getting some work in and really being good listeners to start," Mueller said. "Once we establish a relationship, we can have an understanding of where they place value on things as far as their approach, their emotions and their swing -- 'swing' meaning their mechanics. That's the process. We'll start implementing and trying to impact these guys as soon as possible and try to tell these guys how we feel about any particular situation."
One of those "situations" Mueller and Brumley want to address is batting average with runners in scoring position. Last season, the Cubs ranked last in the NL in those situations at .218.
Mueller didn't want to get into specifics on what he stresses with the players, whether it's improving their on-base percentage or trying to improve their power. It depends on the individual.
"It's just us understanding the guy, knowing where he's at and then implementing the plan and improving and dissecting his weaknesses as well as his strengths and improving all those things," Mueller said.
The former infielder won a batting title in 2003 with the Red Sox, batting .326 that season, and he ended his career with a .291 average. He knows what it's like to play at Wrigley Field after spending two seasons (2001-02) with the Cubs. He addressed the players taking part in the rookie development camp in January, but he didn't talk about Chicago. Instead, Mueller discussed dealing with what he called "the moment."
Players know what that means. Mueller's had a few. On July 24, 2004, he hit a walk-off home run off the Yankees' Mariano Rivera to give the Red Sox the win. It's a game Bostonians feel was a turning point in the team's season, which ended with a World Series championship.
In Game 4 of the American League Championship Series in '04, Mueller delivered a critical RBI single in the ninth, again off Rivera, and the Red Sox won in 12 innings.
Mueller's message to the rookies: "This is going to be real for you guys." Then he showed a clip of his game-winning hits.
There's a lot of talk about pressure. Mueller has a young Cubs team, including Starlin Castro and Anthony Rizzo, who are still developing.
"Is [pressure] real? Where is that pressure?" Mueller said. "There's all these variables out there that we don't know yet until we get in the cage and we start talking and we start understanding these guys and where they place their value at.
"Now, if there's a variable where, when they get runners on second base, they might do something different or tighten up or start thinking differently, yeah, now we address that, and we have to execute our plan to help him have another place to place that value and that tension. That's all part of it. We're in the process of understanding."
So if you stop by the Cubs' Mesa facility this spring, that's what's going on in the batting cages.
"In the end, you're the one who goes up to the plate," Barney said. "I think we're excited about some of the ideas [Mueller and Brumley] have. Having worked with them coming into camp already, I've had some time, I like their ideas, I like where they're at. Our focus is simplified and very complex at the same time. Hopefully a lot of guys buy into it and enjoy it."