How did Mariners’ 2 rookie standouts seemingly come out of nowhere?

May 25, 2023, 12:47 PM | Updated: 3:28 pm

José Caballero of the Mariners celebrates his first MLB hit on April 19, 2023. (Photo by Steph Chambers/Getty Images)

(Photo by Steph Chambers/Getty Images)

Seattle Sports

If you go back a year and tell a baseball fan that the Seattle Mariners would have two rookies standing out early on in the 2023 season, they probably wouldn’t be surprised. But if you told them who those two rookies are, then you might catch them off guard.

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Neither starting pitcher Bryce Miller nor second baseman José Caballero were seen as top-line prospects in the Mariners’ system last year, but they’ve both been invaluable to the team since making their MLB debuts last month.

Their hot starts to their MLB careers serve as a reminder that while highly-ranked prospects like Julio Rodríguez, Logan Gilbert, George Kirby and Jarred Kelenic can make good on their promise in the major leagues, there can also be lesser-known prospects that surprise people by taking off when given the chance.

“I mean, baseball is littered with young players, prospects who are overlooked or not given enough respect for what they do,” Mariners president of baseball operations Jerry Dipoto said Thursday morning during his weekly conversation with Seattle Sports’ Brock and Salk. “We’ve been on this session for 10 minutes and we’ve talked about two of them. Only very recently has the world kind of been alerted to how good we think Bryce Miller is, and similarly with Cabby.”

Let’s take a closer look at what Dipoto said about each Mariners standout rookie.

Why did Seattle Mariners bring up Bryce Miller in April?

The right-handed Miller was somewhat curiously called up in mid-April to make his MLB debut in a start against the Athletics in Oakland. At the time, he owned a 6.41 ERA and 1.32 WHIP in four starts with Double-A Arkansas, but the Mariners said that the underlying measureables they value told a much more positive story.

Safe to say they were on to something. All Miller has done is become the first pitcher since at least 1901 to throw at least six innings and allow four hits or less in each of his first five MLB appearances, according to MLB’s Sarah Langs.

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As for how Miller compares to other pitchers who had good starts to their careers with the Mariners, Seattle Sports’ Brandon Gustafson broke that down on Twitter:

Bryce Miller's first 5 starts compared to some notable former top #Mariners pitching prospects' first 5 starts in innings, strikeouts, walks, ERA and FIP. pic.twitter.com/kIML729TDD

— Brandon Gustafson (@TheBGustafson) May 25, 2023

So what did the Seattle Mariners see from Miller in Double-A that convinced them to pull the trigger on adding him to their starting rotation? Dipoto dove a bit into the “shove scores” that the organization keeps track of internally.

At least in theory what goes into those ‘shove scores,’ we are always looking at the metrics – we call them our pitch grades. And you know, at the time that we were contemplating adding Bryce to the big league staff, we were weighing a body of work. His time in the minor leagues, particularly the 2022 season, was awesome – one of the highest strikeout pitchers in professional baseball, but certainly in the minor leagues, I think, top 10. The physical stuff is excellent and has been for quite some time now. The command has continued to come, and then in those brief few starts in Arkansas after what we thought was a really good spring training, the pitch grades were just off-the-charts good. If we qualify green as good and red as bad, he was bright green, and the action he was creating, the locations he was throwing to, (he was) effectively dominating the things that he could control. That’s what we’re looking for when we’re assessing – how is he managing himself on the mound? Is he executing the things that he can control? And he was no doubt doing those things, and the results are the results. So we look at the expected results versus the actual results, and his expected (results were) incredibly good, and the actual result was just ‘meh.’ We tend to make our decisions more on what the underlying information is suggesting, and that’s that Bryce was actually dealing, (just) his ERA said something differently.

Miller is the third starting pitcher in as many years to impress for the Mariners as a rookie, but whereas there were concerns about the workloads for Gilbert and Kirby in previous seasons as a result of them not pitching professionally in 2020 when the minor league season was cancelled, Miller is in a better spot having been a fourth-round pick by Seattle in the 2021 MLB Draft out of Texas A&M.

“Bryce had a full buildup to get here,” Dipoto said. “Unlike George and Logan before him, he was not a player that was really affected in the same way by the 2020 season. He followed 2020 with a full college schedule and then a minor league progression in ’21, a full season in ’22. We feel like he’s athletic, he’s strong, he maintains his velocity, and there’s really no reason to put a cap on it. We’ll just manage it start to start.”

What is making José Caballero successful for M’s?

While Miller shot up prospect rankings thanks to his impressive minor league season in 2022, the 26-year-old Caballero was an entirely different kind of prospect. He was never considered a blue chipper, and the cancelled 2020 season as well as injuries prevented him from ever really taking off on the farm.

He got off to a hot start in 10 games with Triple-A Tacoma this year, however, going 9 for 27 (.333) with two home runs, a double, a 1.143 OPS and five stolen bases on six attempts. That led to a somewhat surprising promotion to the M’s in mid-April, and even though it took him a week or two to see regular results at the plate, he has taken off in May. He now owns a .283/.392/.433 slash line for an .825 OPS with six stolen bases on six attempts in 25 games with Seattle, including a .350/.471/.550 slash for a 1.021 OPS in 16 games in May.

Dipoto shared that Caballero is maintaining “rates” in the big leagues that he’s shown throughout his baseball career, even going back to junior college ball in Florida before the Arizona Diamondbacks made him a seventh-round draft pick in 2017.

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“I was talking with a couple people down on the field yesterday who aren’t associated with the Mariners but do have professional baseball connections and been around the major league game for a while, and one asked me, ‘Tell me about José Caballero.’ And his partner said to him, ‘Oh, he’s been a good player since college. Nobody knows.'” Dipoto relayed. “… He dominated at Chipola Junior College, he’s been an excellent player through the minor leagues, and even statistically what you’re seeing now in his performance is pretty much on par with all of the rates – the hard hit rates – everything lines up with what he’s done throughout his minor league career. So I think we’re just seeing how good José Caballero is.”

A versatile infielder, Caballero has shown off baseball smarts and even a little power with his first two MLB home runs coming on Sunday and Monday.

“Just such a smart baseball player, and it’s again, you know, beyond his years and experience, at least it seems,” Dipoto said. “He plays like someone who’s played thousands of games. His on-field awareness, his instincts on the bases, in the batter’s box for game situations is just off-the-charts good. He’s brought a lot of energy to our team and it’s been fun to watch. He’s made all the plays at second base. The quality of the at-bat has just been excellent, really, since he’s been called up.

“Now he’s adding a little bit of power to the mix. In spring training I joked with him (after) he just hit a towering home run to left field in Peoria one day. I said, ‘I didn’t realize you had that in your bag.’ He said, ‘Oh, yeah. Watch.’ If you watch Cabby’s BP, it’s real. You know, he pummels balls, he hits balls out in The ‘Pen, off the back of the bullpen wall in batting practice, and now as he gets comfortable in the box in the big leagues, he’s showing that that can be part of his game, too. I don’t think he’s going to be a 30-homer hitter, but if that’s part of his game with the strike zone judgment he has and contact ability and all-fields approach, he is such a pest in the batter’s box and that really makes your lineup long.”

The Jerry Dipoto Show airs live at 8:30 a.m. each Thursday during Seattle Sports’ Brock and Salk. Listen to this week’s edition in the podcast below.