At Chicago's Wrigley Field, where Outfielder Lou Brock played for the Cubs before he was traded to the Cardinals in June, the fans used to get on him. Brock fielded poorly, hit only in the mid-.200s and was not often allowed to show off his strongest baseball talent—base stealing. Overall, it was a situation that did not bring cheers for Lou. It was more likely to provoke barbs like " Brock, as in Rock" from the bleacherites. But when Bing Devine, former Cardinal general manager, traded away two slumping pitchers, Ernie Broglio and Bobby Shantz, to get Brock, he did it with one thing in mind—to juice up the St. Louis base running. So when Brock arrived, Cardinal Manager Johnny Keane let him run on his own and the speedster did the rest. Opening up at full throttle, he has stolen 31 bases since joining the team. He also opened up at the plate—his stance, that is—and has begun hitting his old bugaboo, inside pitches. Batting .344 since June, Brock has drawn nary a boo in St. Lou, where the fans are so pleased by his daring base running and his hitting, including nine home runs, that they are cheering loudly. Last week, as the Cards continued their late run at the pennant, Lou was showing the way with a .412 average (he is now the league's seventh best batter with .310 for the year), three homers, 10 RBIs and three stolen bases—a performance that has Cards' fans agreeing that the name is Brock, as in Sock.