AVONDALE, La. — When Ben Martin played junior golf, his father, Jim, would tell him that his demeanor should be the same every time he walked off a green, whether he made birdie or double bogey. That might explain why Martin seemed so calm when his game briefly unraveled Friday in the middle of the second round of the Zurich Classic, and why he righted himself quickly enough to post the best two-round score ever at TPC Louisiana. Martin, who shot a course-record 62 on Thursday, shook off his first bogey and double bogey of the tournament to finish with a 67 on Friday, putting him at 15 under — three shots ahead of closest pursuer Andrew Svoboda.