Pitching was the Atlanta Braves’ biggest need at the trade deadline. But Austin Riley getting in a groove at the plate could become their strongest second-half development if he can come close to playing like his old self.Over the last few weeks, the Braves’ $212 million third baseman has shown that he can. He has slugged six home runs since the All-Star break after hitting only nine in the first half. In August, he’s hitting .290/.318/.532 and has nine extra-base hits.Corrections at the plate have been the key to his turnaround after a rough first half.“I know I can change a game with the swing of the bat,” Riley said recently.Riley’s surge has come at a good time. The Braves are 8-8 since Aug. 3 and have lost ground at the top of the National League standings. Since the beginning of August, the offense ranks 22nd in runs scored (71), 21st in batting average (.231) and is tied for 28th in OBP (.281).As they head into back-to-back series against the Milwaukee Brewers and Los Angeles Dodgers — the two teams with the best records in baseball — Riley’s surge could make a difference.“Everyone loves the guy, so you pull extra hard for guys like Austin Riley,” manager Walt Weiss said. “He’s one of the leaders on this team, and they see him working and trying to get through his tough first half.”Riley is starting to look like the hitter the Braves needed when they were trying to stay afloat in June.At the time, Riley was getting too twisted in his setup, and pitches away appeared closer than they were. That led him to chase more often.With help from hitting coach Tim Hyers, Riley figured out he was getting underneath the ball and fouling off pitches he typically would have driven. His swing had lengthened, too.Now he’s taller on his backside, and the adjustment has allowed him to stay more controlled throughout the swing. Riley can get more squared to the plate, which puts him in a better position to track the ball out of the pitcher’s hand.“His swing has been a lot more direct and compact,” Hyers said. “He’s able to get the barrel to it and get some contact out front.”As a result, Riley has hit the ball harder than in the first half, when his exit velocity was 90.3 mph and his hard-hit rate was 41.8 percent.Entering Friday, he was tied for the major-league lead in average exit velocity (95.3 mph) since the All-Star break and leads all qualified hitters with a hard-hit rate of 61.2 percent.The Braves benefited from Riley’s adjustments on Thursday. His two-run double propelled them to a 2-0 win over the Chicago White Sox.If he continues this trend during the most important week of the Braves’ season to date, Riley’s resurgence could be what the team can point to if it secures a first-round bye in the playoffs.“When you’re going out there trying to hit 100, you can’t think about mechanics,” Riley said. “You have to go out there and trust your plan. Right now, the work that I’m putting in the cage and the moves in the cage are showing up in games and not having to think about them.”