Rasmus, 19, a right-handed pitcher who was the 38th overall pick, is sidelined until 2008 after having to undergo shoulder surgery.
"We tried to rehab him, but it didn't work," Braves director of player development Kurt Kemp said. "They had to go in there and tighten things up. He should be good to go again next year."
Rasmus worked just 7 1/3 innings in the Gulf Coast League last season after being signed by the Braves to a $900,000 bonus deal. He did pitch in the Instructional League last fall, but was plagued by shoulder discomfort this spring.
Johnson, meanwhile, is having a breakout season in the rookie Appalachian League after struggling mightily last year in the Gulf Coast League.
"He's grown up," Kemp said. "He's worked hard on some things and it has definitely paid off. And he's still just 18."
Johnson, the 24th pick in 2006, was hitting .345 with four homers and 14 RBIs after 13 games for the Danville Braves.
Last season, the left-handed-hitting outfielder struggled even to make contact. He hit .184 with just one homer in 39 games and struck out 49 times in 114 official at-bats.
Johnson, who got a $1,375,000 deal last year, had fanned 12 times in 55 official at-bats this season, drawing six walks.
With a .410 on-base percentage to go with a .673 slugging average, Johnson had a 1.083 OPS -- fourth in the Appalachian League.
The Braves also took a left-handed outfielder with their first-round draft pick this year. Jason Heyward, from Henry County High School outside Atlanta, has yet to sign. He was the 14th overall pick.
Sturtze on the mend: If veteran right-hander Tanyon Sturtze can continue his progress, the Braves may have some bullpen help on the way.
The 36-year-old began an injury rehab assignment with Class A Rome on Monday, pitching a scoreless inning against Columbus. He was also scheduled to pitch more one-inning stints this week.
Sturtze, who has pitched in 269 Major League games, was signed to an incentive-laden contract by the Braves last offseason although they knew he wouldn't be able to pitch before midseason this year. He had rotator cuff surgery last May.
Sturtze began his 30-day Minor League rehab assignment in the Gulf Coast League, where he was limited to 15 pitches each time in his two outings.
In his first game for Rome, Sturtze allowed a hit and a walk while striking out one.
Sturtze was 11-12 with a 4.42 ERA as a starter with the Devil Rays in 2001. As a reliever, he appeared in 64 games with the Yankees in 2005. He was 5-3 with a 4.73 ERA and one save.
Third pitch needed: Matt Harrison started the Double-A Southern League All-Star game on Monday, but the Mississippi left-hander is still far from a finished product.
"He has to trust his curveball and command it for strikes," Mississippi manager Phillip Wellman said. "He has a good changeup, but he needs that curveball to pitch in the Major Leagues."
"They keep telling me to work on it as a strikeout pitch, but it's hard when you don't really have confidence in it yet," the 6-foot-5 Harrison said. "You don't want to get whacked around."
Harrison, 21, came into the season ranked as the Braves' top pitching prospect, but he was replaced be Jo-Jo Reyes, another lefty.
Harrison pitched 1 2/3 scoreless innings for the South in the All-Star Game, working around a pair of two-out singles in the first inning. He has lost his past three regular-season decisions, falling to 5-4 with a 3.23 ERA.
Table setters: The South, featuring seven players from Mississippi, lost to the North, 7-4, in the All-Star Game despite the performances of second baseman J.C. Holt and center fielder Carl Loadenthal.
Holt, the South's leadoff hitter, had three singles and a walk with a RBI and run scored in five trips to the plate. Loadenthal, batting second, was 3-for-5 with a run scored.
It is that type of production at the top of the order that helped Mississippi to a first-half championship. Holt is hitting .319 and Loadenthal is batting .302 with 29 stolen bases -- tied for the Southern League lead.
Guy Cutright is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.