Walker was stationed at the forefront of the dual-hitting-coach movement when he had an assistant, Mike Gellinger, while with the White Sox from 2003-11. That experience has prompted Walker to say he won't do the job any other way, something he told the Braves when he interviewed for their position last offseason.
"I think it's just common sense," said Walker, a former Major League first baseman. "There's so much at stake. These organizations are so competitive at winning and developing players.
"It's not a huge expense. We've got all this money invested in players, and if we can add another hitting coach, it's not a big investment."
Teams already have bullpen coaches to help with the pitching. While some have had an informal assistant hitting coach, several now employ one in an official capacity.
Mike Aldrete took the job with the Cardinals in 2008 and last year gave way to John Mabry, who recently was promoted to the top job when Mark McGwire left for the Dodgers. St. Louis is searching for Mabry's replacement, while Los Angeles hired John Valentin to help McGwire after previously using Jeff Pentland and Dave Hansen in that role.
The Royals and Phillies each added a pair of hitting coaches this offseason, as Andre David will assist Jack Maloof in Kansas City and Wally Joyner will back up Steve Henderson in Philadelphia. The Padres made the move last offseason, hiring Alonzo Powell to work with Phil Plantier.
Both teams in this year's World Series also had assistants, who now have official titles. The Giants moved Joe Lefebvre into the role during the 2011 season, and the Tigers did the same with Toby Harrah this year.
Besides the White Sox, the Cubs and Rangers have carried an assistant hitting coach at times in the past few years. And while the position hasn't always stuck, its trend line clearly is headed upward.
"I think you'll see more and more of that," Maloof said after he was hired Oct. 24. "From a pitching standpoint, it's been that way for a number of years, and I think baseball in general is starting to move toward that format in hitting."
The three clubs that added assistant hitting coaches before this past season -- the Braves, Giants and Padres -- all made significant gains over 2011 in runs scored and OPS, while jumping at least two spots in the National League rankings in both categories.
While the second hitting coach likely qualifies as only one of several factors in explaining that improvement, there are plenty of reasons to believe it played a part. Mostly it comes down to a numbers game.
"Hitting is probably the hardest thing to do in baseball," the Phillies' Joyner said soon after he was hired Oct. 15. "There are so many players that need to stay sharp, and there's only one coach vs. 13 hitters and sometimes more than that if there are guys rehabbing from injuries and staying with the team. There's a need for the hitting coach to be in the dugout. There's also a need for the hitting coach to be in the cages. He can only be in one place at one time."
Assistant hitting coaches aren't found in the dugout during games, due to a Major League Baseball rule limiting uniformed personnel. But there are plenty of other ways they make themselves useful, from throwing batting practice to offering pregame tips to preparing pinch-hitters to breaking down video.
Walker emphasizes the importance of having "another voice," in the conversation between coach and hitter. A second instructor can provide a different viewpoint or reinforce the same one, perhaps in a way that gets through more clearly.
"Being a hitting coach is a lot about your personality, and sometimes your personality might not be right for that situation," Walker said. "Maybe it's the other guy's personality that day."
Walker has trusted both of his assistants to work freely with players, sometimes taking the lead. While a situation in which two coaches at odds would be counterproductive, that hasn't been a problem for him.
"We've got two really smart guys who know mechanics and approach," the Braves' Eric Hinske said during Spring Training. "They kind of feed off each other and work well together. It's just two [sets of] eyes and two people available. That's a pretty big deal."
The assistant hitting coach might not be necessary for every team, but for Walker, it's an indispensable asset and one he sees continuing to gain popularity.
"I'm not smart enough to do it all by myself. That's the way I look at it," Walker said. "And I don't want to miss anything -- I care too much about the players I coach. I care too much about the organization I work for. I don't want my ego or my insecurities to keep me from doing the job the right way."