It’s nearly decision day for the Yankees when it comes to Anthony Volpe . The shortstop was slated to play his final minor league rehab game Sunday with Double-A Somerset, as his 20-day window closed in his rehab assignment from offseason surgery to repair a torn labrum in his left shoulder. But what once was considered almost a formality — that Volpe would reclaim his starting job at shortstop with the Yankees as soon as he was able — is now not so simple. The Yankees have to decide by Tuesday’s game against Texas whether to activate Volpe or option him to the minors. Prior to Sunday’s game against Baltimore in The Bronx, Aaron Boone said no decision had been made, in part because the Yankees have been playing as well as any team in the majors and José Caballero has been a significant part of that success. “Caballero is playing the heck out the position and is playing really well,” Boone said. “That complicates it… José has played himself more playing time.…