Little by little, Triston Casas finding his big-league form

Triston Casas cracked his second home run in three games at Yankee Stadium on Saturday, and has drawn six walks.Sarah Stier/Getty

NEW YORK — Triston Casas appears as if he’s turning the corner. Or, at the very least, continuing to show flashes of doing so.

His weekend in the Bronx has been a spectacle at times. He’s had funny-looking swings, where he appears caught between pitches. He’s had groundouts to shortstop that are products of defensive swings. But the 22-year-old has proven he can hang and then some.

On his first night at Yankee Stadium Thursday, with a packed crowd cheering Aaron Judge, Casas homered off New York reliever Clarke Schmidt and drew a walk. On Friday, Casas singled to right in the ninth and worked two walks. In the second inning of Saturday’s 7-5 loss, Casas drilled a two-run homer to left field off Yankee starter Domingo German. He finished 1 for 2 with three walks.

The homer to left was a poke for a lefthander — just the third lefty homer to left field at Yankee Stadium this season. The walks are equally impressive. In the ninth, when the Red Sox appeared as if they were rallying, Casas loaded the bases in a seven-pitch battle where the rookie didn’t give in.

“I always say to myself, like, you know, you want to be the guy, everybody wants to be the guy, but you’ve got to know how to,” Casas said. “So I think trying to pick out a pitch to hit, I didn’t really get challenged.”

Listen to Casas break down the at-bat.

“I don’t think I saw a fastball that at-bat, so understanding that I could pass the baton to whoever’s behind me and seeing if I can get the job done, it’s just as good to get a walk,” he said, “rather than chasing out of the zone and strike out or put the ball in play just weakly. I’d rather take a walk.”

Before that at-bat, Yankee pitching coach Matt Blake went out to the mound to talk to reliever Scott Effross. It was a sign of respect: Big-league coaches are beginning to take note that Casas is not just some pushover.

There’s an edge to his game. Even with his quiet demeanor, when he steps in the box, he takes that swagger with him.

“That alter ego comes out in that box. There’s a little switch you have to flip, so that’s who I talk to. It’s very demanding, it’s very harsh,” Casas said.

That’s always been the way Casas has carried himself. Last summer, before a random game in Double A Portland, the first baseman said he did not just want to be a big leaguer, but a star. That he’s not here to just take up space on a roster. He wants to make an impact.

He’s hitting just .130 in his first 17 games with the Red Sox, but the progression is there. You see the growth.

“I think at the beginning, I was really looking at the amount the pitches were moving and it was working to my disadvantage,” Casas said. “The fact that they’re moving so much really helps me try to focus on one part of the plate and if it starts down the middle, pretty much guys are making it move and it’s going to be a ball. Focusing on where I want it to start versus where I want it to end has been the biggest adjustment I’ve made.”

Brayan Bello gets his shot in the Bronx

Rookie Brayan Bello takes the ball Sunday evening in another nationally televised game. He has a 4.75 ERA in 11 games (nine starts) this year, but just a 2.67 ERA in his last six starts, striking out 32 in 30⅓ innings. “Big arm. Really good two-seamer. You can see they’re excited about him,” Yankee manager Aaron Boone said. “I know over the last several [games] that he started really throwing the ball well. He threw really well against us, too. He looks like he’s got a bright future for them. That sinker is real” . . . Nate Eovaldi (right shoulder inflammation) came out of his Friday start at Triple A Worcester healthy, but was off mechanically, Sox manager Alex Cora said. Eovaldi threw three innings when the plan was for him to go four, yielding three hits, three runs, two walks, and four strikeouts. The Sox will meet with Eovaldi on Monday and determine what the next steps will be for the righthander . . . Christian Arroyo (illness) still was not feeling well Saturday and missed his fifth straight game.