You always need some level of luck to succeed in baseball, and that just hasn’t been easy to come by for Lawrence Butler for most of this season. Entering Friday’s 6-4 A’s win over the Rockies at Las Vegas Ballpark, the gap between Butler’s actual batting average of .165 and expected batting average (xBA) of .264 was tied for the largest difference of any hitter in MLB. The difference between his expected wOBA (based on quality of contact, strikeouts and walks) of .307 and actual wOBA of .234 was the largest. Meanwhile, the discrepancy between his actual slugging percentage (.256) and expected slugging percentage (xSLG) of .367 was the third-largest of any hitter. It has been a challenging year for Butler as one of baseball’s unluckiest hitters. What better place for his luck to finally change than Sin City? Signs of a turnaround began on Wednesday night, when he delivered a clutch two-run blast against the Brewers that put the A’s ahead for good. Coming off the bench in Friday’s series opener against the Rockies, Butler was the recipient of some more good fortune, scoring the go-ahead run in the seventh inning as a result of an errant throw by catcher Hunter Goodman after Butler had veered too far off third base. It wasn’t all luck, though. Butler created that seventh-inning rally by leading off with a booming double off the right-field wall. One inning later, he added an important insurance run by lining an RBI single to center. “We were talking on Wednesday about how a game like that can get you going,” manager Mark Kotsay said. “Another great day for Law. It’s good to see him get results when he’s put in so much work.”