MILWAUKEE — Scoreboard: Kyle Harrison 3, Rafael Devers 0.

There’s one clear winner from the biggest blockbuster of last season, and it certainly isn’t the Giants, Devers or his former team, the Red Sox.

It’s the guy who struck out the slugger he was traded for three times in their first time facing off Tuesday night.

An added bonus: Harrison gets to ride the good vibes of the Brewers, who improved to 37-21 with their 8-3 win behind the Bay Area kid while the two teams that swung the deal last June wallow a combined 24 games below .500.

And, oh by the way, he’s a shoo-in to make his first All-Star appearance next month.

“It’s been good vibes here from day one,” Harrison said after flummoxing his former team to the tune of one run and a dozen punchouts, maintaining a 1.57 ERA that is lower than any Brewers pitcher in his first 11 starts with the club besides C.C. Sabathia during his iconic stretch in 2008. 

Meanwhile, the loss dropped the Giants to 63-88 since president of baseball operations Buster Posey declared “It’s time to go” after sending Harrison to Boston with two other prospects for Devers last June.

“I think anytime you’re giving up young talent, it’s a bit uncomfortable,” general manager Zack Minasian said this week. “In almost all cases it comes back to what you’re getting in return.”

The Giants were 10 games over .500 at the time and determined Devers was worth the price.

Harrison was warming up in the bullpen when he learned his hometown team had traded him.

“It sucked getting traded that day,” Harrison said, almost a year later. “I remember it.”

Between then and now Harrison was optioned back to Triple-A by the Red Sox (“Like, no but really, what’s going on? My head was spinning for a little”) and then traded to Milwaukee a few months later for Caleb Durbin in a deal that looks even worse than the first one he was a part of.

As the club’s onetime top prospect, a local kid heralded as their future ace, Harrison said he “used that as fuel,” which was still evident when he took the mound.

Brewers manager Pat Murphy had to pull Harrison aside in the dugout after the first inning.

“He was a little amped up, a little out of sorts early,” Murphy said. “I thought it took him off kilter a little bit. I talked to him after the first inning. I said, ‘Hey man, this is about the Brewers. This isn’t about you or where you used to play.’”

Harrison played it coy when asked if there was anyone in particular he was looking forward to facing, say, a certain left-handed hitter who was in the same trade.

His velocity revealed what was left unsaid.

Four of Harrison’s five fastest offerings came in the first inning. The other? In his second showdown with Devers, who also received three of those extra-oomph heaters in the first.

“It’s always going to feel personal,” Harrison said of pitching against the Giants, who drafted him out of De La Salle High School in nearby Concord. “I grew up 40 minutes from that ballpark. I had a great time there and cherish my memories with them. But no man, like yeah, it feels good, but I’ve gotta do it in another five days, so you can’t get caught up in that.”

Check the radar gun readings: Harrison topped out at 97.5 and averaged 95.6 mph with his fastball. In his last full season in San Francisco, his average fastball clocked in at 92.6 mph.

Harrison has also refined his arsenal to focus on his fastball and slider, added a “kick” change he learned from former teammate Hayden Birdsong, shifted his position on the rubber toward first base and raised his typically low arm angle by about 6 degrees.

The move to the first-base side was suggested by Chris Hook, the Brewers pitching coach, and Harrison believes has added life to his slider. The velocity, a frequent topic of discussion during his time with the Giants, is a product of putting shoulder issues behind him.

“I think I easily could’ve got there (with the Giants), but it’s hard to look back on it,” Harrison said. “I’m just glad I’m feeling healthy now. I think that’s the biggest thing.”

The better Harrison gets, the worse the trade looks for the Giants.

“It’s nice for him to see these things come to fruition for him,” Minasian said. “Sometimes with certain guys it’s just a matter of time. But happy for him. Hopefully he doesn’t have a good day tomorrow, and then he can pitch well.”

Spoiler alert: He didn’t wait.

“He’s worked through what he has to work through. I think that’s a testament to him,” Murphy said. “Hopefully he’s starting to believe that, ‘Hey, I’m pretty good if I do X, Y and Z.’”