J.A. Happ explains that it is going to take time to get used to wearing pinstripes and how he felt about his Yankees debut. (1:26)

NEW YORK -- So far, so good for J.A. Happ, who made Brian Cashman look like a genius on Sunday.

In his New York Yankees debut, Happ, 35, allowed just three hits and a run in a strong, six-inning outing in the Yankees' 6-3 win over the Kansas City Royals. The performance could be an early sign that New York's search for starting pitching depth ultimately paid off.

"For him to go out there and give us a strong outing like he did, I'm sure he feels really good about that," Yankees manager Aaron Boone said. "It goes a long way to helping get him settled in because he's going to be important for us."

Happ was acquired Thursday as part of a trade with the Toronto Blue Jays. The left-handed starter was dealt in exchange for infielder Brandon Drury and minor league outfielder Billy McKinney.

With pressure to perform for the sometimes hostile fans in his new city, Happ said the butterflies were aflutter in his stomach at the start of Sunday's game.

"It was kind of weird looking down and seeing the pinstripes on me," said Happ, who has pitched in Philadelphia, Houston, Pittsburgh and Seattle. "But I'm happy to get used to it."

When Cashman, the Yankees' general manager, made the deal, he knew he was getting a veteran pitcher who had a track record of providing stability to a pitching staff. Boone felt similarly, going out of his way to call Happ "underrated." Before the game, Boone added that the southpaw is "more in that upper tier [of pitchers] than people want to acknowledge."

Now 11-6 with a 4.05 ERA, Happ is hoping he can be as valuable to the Yankees' staff as those who brought him to the Bronx believe he can be.

"I'd be lying if I said [there was no pressure]," Happ said. "For sure, you're definitely wanting to have good results. They traded for you. There's some pressure in that.

"But it's fun with these guys playing behind me too. We had some nice defensive plays, and that allowed me to get through six."

Didi Gregorius had one of those plays, scooping a grounder up the middle and stepping on second base before throwing over to first for a key, sixth-inning double play. In addition to the shortstop's stellar play, Giancarlo Stanton chased down a fly ball that took him on a long run into the right-field corner the inning before.

With just two strikeouts to his line, Happ relied on his teammates to get their share of outs.

"As I've told you guys, I'm a big J. Happ guy," Boone said. "Just seeing him come in here with the intensity, with the focus, just really comfortable already, fitting in really well. You always want to see a new player to the team, in a new situation, go out there and have some success.

"We feel like with the addition of J. Happ, it's a significant dude to the rotation that helps in not just the days he pitches, hopefully. But it also makes our staff and our bullpen as a whole better."

Following Happ's departure Sunday, three Yankees relievers combined to strike out six across the final three innings.

J.A. Happ picked up the win in his first start with the Yankees. Mike Stobe/Getty Images

Happ hopes he can continue replicating this formula as the Yankees' push for the postseason really gets going.

"You're in a pennant race, and that's the most exciting thing in baseball, really," Happ said. "That's why I kind of had that in that first inning. Some of the nerves. It was surreal out there."

Happ's solid Yankees debut came on the heels of a difficult July with the Blue Jays. Twice this month with Toronto he failed to make it out of the fourth inning. Defensive miscues and high pitch counts combined to spell trouble. Before Sunday, he hadn't earned a win since June 25.

The Yankees believe Happ can string together more outings like this latest one.

"It was fun to watch him work on our side, to see a guy that's really in command of what he's doing," Boone said. "It's like a guy that's been around so long, but as he gets up in age, he still has the physical ability to cash the checks."

Yankees catcher Austin Romine, who was seldom shaken off in this game by Happ, said the starter's years of experience will pay off.

"He knows how to pitch. He's been in situations before where he's got to pitch well," Romine said. "[Sunday] was a really professional performance, being on the mound and calm, like he's been there before. It was weird, but it almost felt like I had caught him before. We were so much on the same page."