SEATTLE -- The comp was out of left field and lofty enough to aggressively raise an eyebrow. It wasn’t just that it was of a player who was thriving well before Julio Rodríguez was born, or that this particular star thrived in a different sport. It was more of the “wow” factor that the comp possessed during his rookie season, when he was also just 21 years old, and the way he transcended his position, and as such, the game.

“Randy Moss. Julio reminds me so much of Randy Moss.”

Those words come from Yo Murphy, a former teammate of Moss with the NFL’s Minnesota Vikings in the late 1990s and who now works with Moss at House of Athletes, an athletic performance facility in Tampa, Fla. It’s also where Rodríguez has trained in each of the past four offseasons, honing the skillset that has taken off so dramatically and -- at least to everyone but him -- so unexpectedly in his first big league season. 

And now, they’ll all be on display on the biggest stage, as Rodríguez is set to play in his first All-Star Game on Tuesday at Dodger Stadium, where he’ll be the only rookie. He’ll also participate in Monday’s T-Mobile Home Run Derby, looking to become the youngest winner in the event’s history.

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Rodríguez is here because he’s been one of the American League’s most productive outfielders, especially the past two months. He’s long been touted for his bat speed and pull power. Early scouting reports suggested that his floor would be as a bulkier corner outfielder who could hit 30-plus homers but might strike out a lot while possessing an average glove at best. Yet virtually no one discusses his speed, which as recently as this spring was graded 45 by MLB Pipeline on a 20-80 scouting scale.

“I didn't see it coming,” Mariners manager Scott Servais said. “Until I got to Spring Training. It was one of the first days we ran the bases as a team, early camp, and the way he's flying around the base like, ‘Oh my God, this is different.’ And you start seeing him move in the outfield, and his ability to close on balls.” 

It’s not just Rodríguez’s 21 stolen bases, which are second in the Majors, or the 29.6 feet-per-second average sprint speed, which ranks in the 97th percentile or the six outs above average he’s posted playing a plus center field, which ranks in the 94th percentile. It’s how he’s leveraged the raw tools he had after signing as a 17-year-old out of the Dominican Republic and better honing them by working with Murphy, whose Rolodex includes 140-pound snowboarders to 350-pound lineman.

The two connected through Rodríguez’s agent, Ulises Cabrera, who for years sent many of his younger clients from the Dominican Republic to Murphy. Rodríguez knew he was fast, but his body movements were all over the place.

“It made a huge difference,” Rodríguez said. “Because I feel like before, like two years ago, three years ago, I had like a nice speed but when he saw me he said, ‘OK, we have room to improve that's going to make you faster without you actually getting faster, just by running better.’” 

The buy-in came from video, with Rodríguez going through a battery of drills then observing and correcting his flaws. Once muscle memory took over, he began working more thoroughly with practical drills in the outfield.

“Once he’s on the basepaths, it has to be second nature, because you can't be focusing on thinking about how to push this, that and then you’re getting picked off consistently,” Murphy said. “Eventually, it became part of his running style. When he moved, that’s how he moved, and obviously, you’re seeing it now.”

Rodríguez surprised his manager, the front office and many teammates with his speed and defense this spring. But what about Murphy, who has seen him behind the scenes from the beginning?

“I’ll be honest, I expected him to earn a spot this year and I expected him to have some flashes because I saw some flashes,” Murphy said. “So I knew he was going to do some things, I just didn’t think he’d be in there every day and have the opportunity and then take advantage of every opportunity. It’s amazing. It’s something else.”

Murphy vividly recalls a preseason practice in 1998, the year Moss set the NFL rookie record for most touchdown catches in a season. Moss was turning Dale Carter, a four-time Pro Bowler to that point, around in circles. 

“One of our coaches or somebody said something to me like, ‘It's amazing what this guy can do.’ I said, ‘No, it's amazing that he knows what he can do,’” Murphy said. “That's the thing with Julio -- he knows what he can do. And so when guys approach it like that, I mean, there is no limit.”