Johnson will be the fifth outfielder while Blake DeWitt, who many thought would be the starting second baseman, will back up second and third. The Cubs considered sending DeWitt to the minors to work on his defense, but he'll now fill a utility role.
"I asked him to play nothing but second," manager Mike Quade said. "We'll change that a little bit. We will continue his work at second, but we're going to ask him to take some balls at third and look at him as that being a possibility, as well.
"We wanted him to get a chance to get as much work as possible at second base. But that's still a work in progress."
Barney and Jeff Baker will share most of the starting assignments at second, even though both are right-handed hitters. Baker hit .350 against left-handed pitching last year, and he'll most likely lead off against lefties again this season.
Barney, meanwhile, has been the most impressive player in camp.
"He's played himself into significant playing time," Quade said. "He does a lot of things out of the batter's box that you really like.
"He's given himself every chance to be an important part of this infield. And now we'll go north, and we'll see what happens in April. That's what really matters."
Barney remains the only backup shortstop on the Cubs' roster.
Johnson was batting only .206 in 34 spring at-bats -- compared to .161 for Perez, who was optioned to Triple-A Iowa -- but Johnson has experience on his side. The eight-year major league veteran played for the Cubs in 2008 and 2009 before signing with the Dodgers last season. He batted .287 in 498 at-bats in his previous stint with Chicago.
The next round of cuts for pitchers and catchers will come Friday and Saturday. Still to be decided are the fifth starter role, two bullpen spots and a backup catcher.
Quade said he hopes to have all of this resolved before Sunday, when the truck leaves for Chicago with the possessions of the 25-man roster.
Moore, 27, and Scales got caught up in a numbers game in the infield. Neither did anything to hurt his cause this spring. Moore hit .351 with three home runs and nine RBIs. Scales, a lifetime minor leaguer who was looking to stick with the Cubs at age 33, batted .391.
Ojeda, who came up with the Cubs and played in Chicago from 2000 to 2003, couldn't get healthy enough to impress.
Camp was a non-roster invitee who batted .200 this spring.
Bruce Levine covers baseball for ESPNChicago.com and ESPN 1000.