Mission accomplished, and then some.
McCann is batting .386 with five homers and 10 RBIs in his last 12 games, and Ross said taking that bat out of the middle of the lineup "is a tough thing to do." Ross said he takes pride in playing well enough in his few starts so McCann can take the full day off.
Tim Hudson overcame a first-inning fall to pitch six innings and Jordan Schafer made a couple of nice plays in center field, helping Atlanta to its fifth consecutive win and 10th in its last 12 games overall.
Mark Reynolds hit two first-pitch homers for Baltimore, including a two-run shot to center field in the fourth. Reynolds' 17th homer landed about 10 rows deep in the left-field seats in the sixth.
Nick Markakis' seventh-inning homer off Scott Linebrink trimmed Atlanta's lead to 5-4, but the Orioles (35-45) couldn't complete the rally. They have lost five straight and are 10 games below .500 for the first time this season.
Markakis finished with three hits one day after his career-best 19-game hitting streak came to an end.
The Braves scored all their runs in the fourth, taking advantage of a key mistake by Luke Scott. Dan Uggla hit a sinking liner to left with two out but Scott dropped it. Uggla was awarded an RBI single.
"That's a tough play, either way, but that's not what beat us," Baltimore manager Buck Showalter said.
"He's great," said Hudson, who also played with Ross at Auburn University. "Back at Auburn, he had a knack for hitting big homers. It's happened so far here."
Arrieta said Ross hit a fastball "right in the middle" of the plate.
"I got two quick outs," Arrieta said of the inning. "Had a guy 0-2. Then everything fell apart.
"It's a terrible feeling. That's it. That's all I've got."
In his first at-bat, Ross surprised Arrieta and the Orioles with a bunt single.
Hudson (7-6) wasn't sharp but was helped by two impressive grabs by Schafer. After hauling in Reynolds' drive at the wall in the second, Schafer made an over-the-shoulder catch on the warning track on J.J. Hardy's fly ball in the fifth.
Hudson gave up three runs and eight hits, struck out six and walked three.
Arrieta pitched five innings for the Orioles, yielding five runs and six hits.
Hudson's night began with an unexpected tumble off the mound. His cleats stuck in the dirt as he was starting to deliver his third pitch to leadoff hitter Hardy. He kept the ball as he landed sideways, then tumbled onto the grass.
Hudson, grinning and obviously embarrassed, tipped his cap to the fans in a self-effacing manner as third baseman Chipper Jones held his glove over his face to hide his laughter.
"I looked like a big stooge out there," Hudson said. "Something like that, you have to laugh about it."
Hudson regrouped to strike out Hardy and he continued to smile -- especially when looking over at Jones -- the rest of the inning.
"I've never been more embarrassed for a teammate than when he fell before a sellout crowd on fireworks night," Ross said.
There was rain, but play continued, in the final two innings. There was a brief delay in the middle of the eighth as dry dirt was applied to the pitcher's mound and around home plate.
The Braves optioned RHP Cristhian Martinez to Triple-A Gwinnett and recalled RHP Cory Gearrin for the third time this season. ... Ross hit his only other grand slam on Aug. 31, 2010, against the Mets. ... The Orioles fell to 6-11 in interleague play and 4-14 in their last 18 road games. ... Attendance was 36,259.