Evan Gattis had a solid — though injury-interrupted — season with the Mississippi Braves in 2012. He had a good winter ball campaign. And he was impressive in spring training with Atlanta. But, still, no one could have expected the impact he has had with the Braves. Gattis, who belted his first career grand slam on Wednesday, has 10 home runs in 37 games. According to MLB Network, only two Braves rookies have gotten to 10 homers faster: Wally Berger in 1930 and Jeff Francoeur in his magical summer of 2005. Gattis also has 27 RBIs. But Gattis is not alone among former M-Braves who have been pleasant surprises for Atlanta, which has won six straight to reach 28-18 and open up a 4½-game lead in the National League East. Jordan Schafer, the onetime No. 1 prospect who fell hard and fast, seems transformed in his second tour with the Braves. The less cocky, more mature Schafer is hitting .309 with 12 runs, a team-best six steals and a .434 on-base percentage in 31 games. He is also a good outfielder with a strong arm. You actually find yourself wishing he played more. Then there’s Cory Gearrin and Luis Avilan, who have helped ease the sting of injuries in the Braves’ bullpen. Gearrin has a 0.87 ERA in 25 appearances, lefty Avilan a 3.06 in 21. They weren’t expected to be key contributors this season but have answered the bell. So, too, has Julio Teheran, also a former No. 1 prospect. After a so-so 2012 season in Triple-A, he won the fifth starter job in the spring and is 3-1 with a 3.99. The Braves have hardly missed Brandon Beachy, who is due back from injury soon. P.S. Cory Rasmus made his MLB debut on Wednesday, allowing two homers in 1 2/3 innings but finishing off Paul Maholm’s sixth win. Rasmus is the 72nd M-Braves alum to make The Show. … Happy 57th birthday to Buck Showalter, the ex-Mississippi State standout whose Baltimore Orioles are 25-21 and hanging tough in the American League East race.