BALTIMORE — Instead of challenging fellow shortstops Gunnar Henderson of the Orioles and Bobby Witt Jr. of the Royals for an All-Star Game appearance, Anthony Volpe ended his first half in miserable fashion.In addition to being mired in a horrendous slump that’s lasted over a month, Volpe helped boot away a victory Sunday, as his error with two outs in the bottom of the ninth allowed a run to score and extended the inning in a 6-5 defeat to the Orioles.Of the play in the ninth, a simple grounder by Ryan Mountcaste, Volpe said he was “still processing it. To me, it’s a routine ground ball a million times over.”Anthony Volpe couldn’t collect the ball in time to get a force out at second base. Screengrab via X/@TalkinYanksInstead, he said his footwork was off and he didn’t handle the ball properly in time to get the force at second.And then Cedric Mullins lofted a fly ball to left that Alex Verdugo misplayed into a game-winning double.Volpe said of his error, “It’s a play I know I’ve got to make and anything after that doesn’t matter.”“It’s tough,’’ Aaron Boone said of the play. “There’s no one you’d rather have the ball hit to. It happened and we have to move on.”But it symbolized how bad a stretch Volpe is in.Following an impressive start to his second season in the majors, Volpe entered Sunday with just a .602 OPS in his previous 81 games.And since June 6, it’s been worse.Over 34 games prior to Sunday’s loss, when he had a double and scored a run, Volpe had an OPS of .424 — with no homers — in 154 plate appearances.“I think we’re still seeing a young player working through it,’’ Boone said. “It’s no secret some of the swing changes he made over the winter, he’s taken his lumps here the last few weeks. But I do think it’s part of a 22-year-old gaining experience, learning, on his way to being a more complete and finished product.”Anthony Volpe reacts after committing an error in the ninth inning Sunday. Screengrab via X/@TalkinYanksThe signs haven’t been there lately.In the offseason, Volpe worked to alter his approach and make more contact, with the hope it wouldn’t rob him of any power after he hit 21 home runs as a rookie.But for much of the season — whether it’s been at the leadoff spot or down in the order — Volpe hasn’t done much of anything.Go beyond the box score with the BombersSign up for Inside the Yankees by Greg Joyce, exclusively on Sports+.Thank you“I don’t think, in the end, it’s going to [hurt his power numbers],’’ Boone said. “Are there some growing pains to get there? I think he gets back to, eventually, where there is power in his game.”The process, at least this season, has been rough.“Going through this has been a little bit of a challenge,’’ Boone said.Anthony Volpe makes a throw during the fifth inning of Sunday’s game against the Orioles. APHis .666 OPS on the season is worse than all but two qualified AL shortstops and continues to drop.Prior to the game, Boone talked about the All-Star break being good for players both physically and mentally.Perhaps this proves to be the case for Volpe, who also struggled in the second half last season.For the Yankees to get back to the heights they reached over the first two-plus months of the year, Volpe will have to be the player he was for most of that time.