Frank Wren was in an especially good mood Saturday, and he had reason. The sun was shining and his rebuilt Atlanta Braves were about to play an exhibition against the New York Yankees, and the rebuilt Braves hadn’t yet lost a game that counted. The guess here is the 2013 Braves won’t lose very many games that do count. From the sound of it, their general manager might make the same guess. Asked if this was indeed the best Braves’ club he had assembled, Wren said, “I think so, just from seeing what these guys are capable of. It’s by far the most athletic team, and it has the most speed, the most powerful, the most balanced whether it’s left- or right-handed. Now we’ve got to go play.” Someone asked if he was concerned about the Braves lacking a clubhouse leader in the wake of Chipper Jones’ retirement. “We’ve got lots of candidates,” Wren said. “To be honest, that’s probably the least of my worries.” What, then, might be his greatest fear? “Just if we can stay healthy. If we can do that, I’ll be a happy man.” Here we pause to note where the Braves were in October 2007, when Wren succeeded John Schuerholz. The new GM inherited a farm system that had been decimated by the Mark Teixeira trade, and he’d been handed a starting rotation that would fall to pieces in 2008, a season that would see the Braves lose 90 games for the first time since 1990.