PITTSBURGH -- Quinn Priester wrote it on his mirror with a dry erase marker, and the message sat there every day to remind himself of what his potential was, what his goal was: “First-round Draft pick.”

That goal was accomplished on Monday, when Priester, the No. 18 overall pick in the 2019 MLB Draft, officially signed with the Pirates. He agreed to sign for $3.4 million, according to MLB Pipeline’s Jim Callis, with the pick’s slot value set at $3,481,300.

“Going into last summer to right now, I’d always had the rough idea that I could be a Day 1 guy,” Priester said in a news conference at PNC Park on Tuesday, “but I knew if I worked hard enough and worked at it -- really put everything I had into it -- that I had a chance to be a first-round guy.”

For his parents -- his father, Andy, and his mother, Chris -- the reality didn’t truly hit them until even as late as February. But they had an idea as early as summer 2018, when Priester traveled to Tampa Bay for the Perfect Game National Showcase at Tropicana Field.

“I remember [Chris] called me or sent a text … and somebody had tweeted, ‘Who’s going to take him in the first round?’” Andy recalled. “And I think [Chris and I] were like, ‘Really?’ I think there were 500 kids there. So that was the first time that I think, for me, it was like, ‘Holy cow, this really could be that strong of an opportunity.’”

Priester’s accomplishments on the diamond certainly point to a top talent. In his senior year, Priester posted a 1.00 ERA with 91 strikeouts across 60 1/3 innings as the ace of the Cary-Grove (Ill.) High School pitching staff. He throws his heater comfortably in the mid-90s and can hit 97 mph when rearing back, helping vault him to the No. 19 spot on the Top 200 Draft prospects list.

MLB Pipeline’s Jonathan Mayo even went so far as to write that Priester may be the prep pitcher most ready for a quick rise into the Major League ranks.

But unlike the many others going in Day 1 of the Draft, Priester didn’t rely on the help of private coaches or expensive academies to put him on the national scouting lists. Instead, he took advantage of social media, using crowdsourcing to get his edge on the mound. Under the instruction of YouTube channels and Rob Friedman’s Twitter account, @PitchingNinja, he picked up new tools of the trade.

“I started to get fascinated with the body,” Priester said. “This person can throw 95 [mph] from the side -- Chris Sale can throw 100 from over here -- then another guy can throw 100 from up here. How does that work and how do they use everything else differently other than their arms? That’s when I started to get interested with [trying] to replicate that.”

It didn’t always work, of course. Chris called her son “a tinkerer,” someone who would go into the bullpen and try any number of things to make his already exceptional stuff better. But she recalled one instance in which it was a total failure as he tried to replicate Jake Arrieta’s crossover step toward the plate.

“He tried it, and he was like, ‘It was terrible,’” Chris said. “So he was like, ‘Forget it. I’m not doing that, throwing that away.’ That was the first time I remember him saying that.”

And what Priester sees and learns from doesn’t necessarily have to reflect his own game. His favorite pitcher to watch, NL Central foe Kyle Hendricks, throws a good 10 or more mph slower than Priester, but Hendricks has used his full arsenal to produce a 3.06 ERA over his six-year career.

“I like to pick up stuff from everyone, but I still like to be myself,” Priester said. “... But if I pick up something, it’s like, ‘This is easy.’ I spent five minutes on YouTube, and I’m that much better.”

The self-starter mentality grows out of not only his curiosity, but also his competitive nature and leadership mindset. A two-sport athlete in high school, Priester was often the one to show emotion in the dugout, to rally his teammates toward an undefeated 2018 football season, and to keep things positive and forward-looking.

Pirates general manager Neal Huntington said these qualities are often as important as the physical traits of a prospect.

“Those are all absolutely crucial,” Huntington said. “You can have one but not the other, and you probably have a pretty decent amateur player, but to be a really good Major League player, there’s a huge need for both sides. You need to be really talented, but you also need to be really driven.”

Priester’s professional journey will begin on Wednesday, when he’ll head to Bradenton, Fla. His debut is slated to come as part of the Pirates’ Rookie-level Gulf Coast League team, though the date is still yet to be determined. Priester is eager to use his learner’s mindset to take on his first task, a goal that he said remains scribbled on his mirror below where “first-round Draft pick” was erased: developing a solid changeup to keep hitters off-balance.

“I’m just going to listen,” Priester said. “I’m going to listen as much as I can, take as much information as I can, and I know that a lot of those guys have reached the big leagues. I have not. So they know what it’s like, they’ve done it before, and I haven’t.”