CHICAGO — It’s no coincidence that Pete Crow-Armstrong is suddenly becoming a defensive liability right after his expletive-laced taunting of a female fan went viral on social media. The Chicago Cubs have long heralded him as an all-world defender, while also acknowledging his struggles to control his emotions.A mental reset, of sorts, is coming with Thursday’s off day, a well-timed break for a Cubs team that is currently flailing in all phases of the game. But this moment appears to be especially uncomfortable for Crow-Armstrong, who signed up to be the new face of the franchise when he agreed to a six-year, $115 million contract extension before Opening Day.The boos echoed throughout Wrigley Field on Wednesday night after Crow-Armstrong’s error in center field, a Little League-style misplay that handed the Milwaukee Brewers three early runs on the way to a 5-0 victory and a three-game sweep of their big-city rivals.“Genuinely laughable,” Crow-Armstrong said. “That just can’t happen.”Mistakes are part of the game, but this one occurred within a much larger context.Go back to Sunday afternoon on the South Side, where Crow-Armstrong tried to make an impossible catch at the Rate Field fence and barked a vulgar response back at a woman who was heckling him, part of the jeering from some Chicago White Sox fans whom he felt crossed a line.Once the video of that incident surfaced and became a national story, Crow-Armstrong met with reporters at his Wrigley Field locker before Monday’s game and said he regretted his poor choice of words and the bad example it set for young baseball fans.