Diamondbacks shortstop Cliff Pennington began his career with the Oakland Athletics in 2008 when third baseman Eric Chavez was hitting his roughest patch ever. From 2008 to 2010 the three years the two overlapped in Oakland Chavez played a total of 64 games due to a variety of injuries. Back spasms torn labrums bulging disks — Chavez could have marketed his own depressing version of “Operation.” “He couldn’t catch a break” Pennington said. “It was one thing or another.” Now Chavez is more or less healthy. A right oblique strain landed him on the disabled list for most of June and the Diamondbacks took it easy on him around the All-Star break while he dealt with a hip issue. Because of a platoon with Martin Prado at third he probably won’t reach 100 games like he did last year with the Yankees but the days of season-ending surgeries are likely over. But the idea that Chavez has become a better hitter because of those injury troubles? That isn’t something Pennington can quite wrap his head around. “When he swings it’s about as good a swing as you can have” Pennington said. “It’s always looked like that to me.” Still that’s exactly what Chavez insists has happened. Entering Friday’s series opener against the San Diego Padres at Chase Field the 15-year veteran was hitting .306 which would be a career high at season’s end. The natural swing is still there but Chavez is making more out of his at-bats. He has the highest batting average on balls in play (.328) and second-highest slugging percentage (.529) of his career. He’s striking out just 15.8 percent of the time down from his career average of 17.2. He’s making contact more often — on 84 percent of pitches swung at compared to 79 percent for his career.