The baseball people who knew Joe Musgrove best and scrutinized him most carefully saw this coming. Maybe not the no-hitter Friday night against a Rangers lineup that included four rookies and two players with one-plus years of service. But the potential breakout, sure.

Musgrove’s promise was evident in his final five starts for the Pirates in 2019, when his new, shortened arm action began translating into results. And he flashed it again at the end of ’20, when he again finished strong after missing time with right triceps inflammation.

So there he was Friday night, “committed to his identity” in the words of Oscar Marin, his former pitching coach with the Pirates, pitching the first no-hitter in the Padres’ 52-year history. That identity, Marin said, is of a pitcher who is best when he is spinning the baseball. And sure enough, the last 35 pitches of Musgrove’s 112-pitch no-hitter were sliders, curveballs and cutters, according to STATS Perform.

Marin, who was the Rangers’ bullpen coach in 2019 before joining the Pirates in ’20, made sure to watch his former pitcher face his former team, calling it “super exciting” and Musgrove “one of the best people I’ve met in baseball.” Ray Searage, the Pirates’ pitching coach during Musgrove’s first two seasons with the club, also was ecstatic, saying he sent his former pupil a text message afterward: Congratulations. Well-deserved. All that hard work is starting to pay off.

“This guy has worked his ass off, day in and day out, not only physically but mentally, trying to make himself a better pitcher,” Searage said. “Being in San Diego has relieved him a little bit of the burden that was there in Pittsburgh. He’s able to just be himself. He’s going to grow. He’s going to mature. And you guys are going to be saying, ‘Where was this guy?’ It was always in there.”

Musgrove, 28, was part of the Pirates’ return from the Astros for right-hander Gerrit Cole on Jan. 13, 2018, along with corner infielder Colin Moran, right-hander Michael Feliz and outfielder Jason Martin. The trade, completed by former Pirates general manager Neal Huntington, looks far better today than it did then, especially considering that Cole at the time was not yet a consistently dominant ace. The Pirates, under their current GM, Ben Cherington, should be happy if their four-player return for Musgrove works out as well.

The turning point for Musgrove came when he altered his delivery late in the 2019 season. Instead of dropping his arm after separating it from his glove, he began drawing it closer to his waist, enabling him to stay on top of the ball and be more consistent with his release point. In his final five starts of that season, he produced a 2.89 ERA in 28 innings, striking out 32 and walking only five.

“He was just messing around with it in the bullpen,” Searage recalled, referring to Musgrove’s mechanical adjustment. “I kept an eye on it. I was like, ‘OK, I’m not going to say anything. I’m just going to watch how this plays out.’ It didn’t take anything away from his stuff.”

Quite the contrary.

“Not everyone can immediately shorten their arm action and immediately be good, but guys couldn’t hit his breaking ball anymore,” one rival executive said. “When you throw strikes and get groundballs, then add strikeouts, you’re talking about an ace.”

Musgrove seemed poised to take a major step forward in the shortened 2020 season, then was sidelined from Aug 12 to Sept. 2 with right triceps inflammation. But in his final three starts, he got back on track, striking out 29 and walking only three. The Padres were among the clubs that took notice.

Yet, Musgrove still wasn’t finished evolving. Under Padres pitching coach Larry Rothschild, he has altered his pitch mix, making far greater use of his cutter. Granted, his sample size consists of only two starts. But Musgrove has gone from 39.1 percent fastballs in 2020 to 19.5 percent, according to FanGraphs, and from 5.9 percent cutters to 24.7 percent. “He’s got about seven pitches,” Marin said, chuckling.

Searage, though, worries about Musgrove throwing his cutter too often.

“I don’t like that. The cutter is a very forceful pitch. It puts a lot of stress on the elbow,” said Searage, who is not currently working in baseball. “Before (Taillon) got hurt (requiring Tommy John surgery in May 2019), I remember one start in Texas, it was like, ‘Whoa, we’re throwing cutters to both sides of the plate.’ I mean, it was over-usage. I don’t know if you could attribute (the injury) to it. It’s a good pitch, but if it’s overused — this is my opinion now — I think you set yourself up for an ‘owie’ that is going to take some time to come back from.”

Searage was careful to add that he did not want to come off sounding like he was telling his former pitchers what to throw, saying, “In the heat of the battle, they’re going to do what they want to do. It’s their butts out there.” He also reserved special praise for Musgrove’s leadership, saying, “Joe is not afraid to stand up in front of his teammates and say something.”

He didn’t need much help in the Padres’ 3-0 victory Friday night, striking out 10, walking none and allowing his only baserunner when he hit Joey Gallo with two outs in the fourth inning. Musgrove, a San Diego-area native, won’t be that good every game, and all pitchers face a risk of injury. But for now, the Padres can look forward to keeping him through at least 2022, and possibly beyond if they sign him to an extension.