NEW YORK — Gerrit Cole has become a mentor to Cam Schlittler. At Fenway Park last week, Cole made sure to watch the end of Schlittler’s bullpen, and afterward the two walked slowly back to the visitors dugout together. On days when neither is pitching, Schlittler makes sure to stay near Cole in the dugout to soak up as much knowledge as he can.On Tuesday, Schlittler once again leaned on Cole, this time to help him navigate the rest of an uncharacteristically rough outing. Cole suggested Schlittler should incorporate more of his curveball; otherwise, Schlittler’s night might end up much worse. It was among the lessons the 25-year-old learned over four innings, his shortest start this season.In the worst of his 32 career starts, he allowed six earned runs and four home runs — both career highs — to the Detroit Tigers in a 9-3 loss that extended the Yankees’ losing streak to six games.“It’s my job to come in here and stop that bleeding,” Schlittler said. “I couldn’t get that done. I put the team down four in the first. It’s not encouraging, especially against a guy like (Tarik Skubal). It’s taken a while to experience an outing like that. I just got to take what I can from it and get ready for next week.”What frustrates Schlittler is he knew the scouting report better than what he showcased Tuesday. He knew that the Tigers were one of MLB’s best teams at hitting fastballs. Detroit entered Tuesday as the second-best offense in terms of xwOBA, which measures contact quality.Schlittler is one of the most analytically focused players the Yankees employ, so he was annoyed that he strayed from the game plan and instead tried overpowering the Tigers with what he does best — almost exclusively throw fastballs.He also knew the Tigers particularly struggled against curveballs; they had the fourth-worst xwOBA against the pitch this season. He went from 6 percent curveball usage the first time through Detroit’s order to 30 percent the second time through.Riley Greene circles the bases after homering against Cam Schlittler. (Jim McIsaac / Getty Images)Schlittler struggled to get out of the first inning, mainly because the Tigers were not missing any of his three fastballs. Of the 21 swings on his 36 pitches in the inning, they whiffed on zero of them. Kerry Carpenter, Riley Greene and Spencer Torkelson all took him deep in the first. By the time Schlittler walked back to the dugout, Detroit led 4-0.“I’m confident he’ll grow from this,” Yankees manager Aaron Boone said. “This will be something that fuels him and allows him to see where he can make adjustments moving forward.”Schlittler said that once Greene hit his homer, he should have adjusted to throw more curves, but he didn’t. It was the latest learning experience for Schlittler, who has impressed the Yankees with his ability to self-scout.Boone said that Schlittler’s self-scouting caught his attention last season. The Yankees realized the right-hander wasn’t overwhelmed by the scouting, game planning and adjusting required of every major-league starter. Boone said there are times when they’ll have to relay information to players and make it as simple to understand as possible, but not with Schlittler.“It didn’t give him anxiety,” Boone said. “You didn’t feel like you had to simplify things just to have him go out there and be comfortable. You could bring him things, and he could work on them and not be overwhelmed.”Schlittler’s ERA rose from 1.62 to 2.08 on Tuesday. Even after his poor outing, he still leads the American League in ERA, with Tampa Bay’s Drew Rasmussen second at 2.45.Some may take this as an opportunity to suggest Schlittler’s arsenal doesn’t work, and that he’ll have to adjust as soon as his next start. He does not look at it that way. His next outing could come against the Rays next week, and Tampa is the worst-performing team in MLB against fastballs.“It depends on the matchup, and I think it depends on the hitters and certain situations,” Schlittler said when asked if he needs to simply throw more curves in every start. “Knowing (the Tigers) like to put the fastball in the air, that’s probably something I should have established early on.”The Yankees’ ace was amped for his matchup against Skubal, who has won back-to-back AL Cy Young awards. Schlittler has pitched like the early favorite to win the award this year and to potentially start for the American League in the All-Star Game. He has bigger goals than accomplishing both. Immediately after this start, he was already diagnosing what went wrong, so he can once again perform like the best pitcher in the league.“It took me 30-plus starts to finally get my teeth kicked in,” Schlittler said. “There are lessons to be learned from this.”