As he took his place in the batter’s box in the ninth inning on Sunday at PNC Park, Adam Frazier had 392 big league at-bats, 109 hits and 39 RBIs under his belt. The former Mississippi State star then did something he had not done in his previous 135 MLB games: He delivered a walk-off hit. Pittsburgh beat St. Louis 4-3 on Frazier’s single off Brett Cecil. Frazier, who was batting .361 in late May, had been scuffling mightily heading into the All-Star break. During the time off, he did nothing baseball-related. “Everybody needs a mental break,” he told mlb.com, “to get away and live life like normal people for a few days.” It appears to have helped. The Pirates’ super utility player is 6-for-13 in the three games since the break, helping the Pirates take two of three from the Cardinals in the weekend series. For the season, the second-year big leaguer is batting .267 with three homers, 29 RBIs, 36 runs and seven stolen bases in 70 games. The Pirates (44-48) are 7 games back of first-place Milwaukee in the National League Central heading into a four-game home series against the Brewers.