Griffin could be a teenage big leaguer. Here's how history says that might go

When MLB Pipeline's No. 1 prospect Konnor Griffin launched not one, but two home runs over the replica Green Monster and out of JetBlue Park on Tuesday, social media servers seemed at risk of overheating.

Enthusiasm was already elevated for the 19-year-old Pirates shortstop, and performances like that will continue to push the hype machine into overdrive. If there are more such feats this spring, it will become increasingly difficult to keep Griffin off the Opening Day roster if making a merit-based decision.

The ninth overall pick from the 2024 Draft is expected to debut at some point during the 2026 season, but it could happen before his 20th birthday arrives on April 24. How many 19-year-olds have made the jump in recent years? What can reasonable expectations be for the most precocious talents, especially when the gap between the Majors and Minors is as large as it's ever been? Let’s explore.

Over the past 40 years, there have been 18 position players to debut as teenagers. Reaching the pinnacle of baseball at an age when many are freshmen in college is an incredible feat. The list is loaded with four Hall of Famers (Ken Griffey Jr., Adrian Beltré, Iván Rodríguez, Andruw Jones), a 696-homer shortstop in Alex Rodriguez and a number of MVP winners, including Bryce Harper and Mike Trout.

A teenage debut is often indicative of a special career trajectory. But there's just one catch: Not everyone from this incredible list was a star immediately. In fact, the majority are not.

The average debut year OPS+ of these rare teenagers is 75, meaning they are about 25% below MLB-average offensive performance when adjusting for ballpark and run-scoring environments.

The performance improved when we filtered those teenage debuts to a group that received at least 200 plate appearances, suggesting they at least treaded water at the Major League level. Those eight players combined for a 98 OPS+, or just about league-average performance. This suggests initial expectations likely ought to be tempered for Griffin.

So, curb our collective enthusiasm, right? Well, perhaps not.

If we refine our search down to teenagers who reached 400 plate appearances in their first full season since 1986, that's where things become interesting. Griffin could reach that threshold if he debuts early and shows he belongs at the highest level.

It's a short, elite list: Harper, Griffey, Juan Soto and Edgar Renteria. That includes a Hall of Famer (Griffey), a two-time MVP (Harper), a six-time Silver Slugger through age 26 (Soto) and a five-time All-Star and World Series hero (Renteria).

They averaged a 118 OPS+ in their teenage debut seasons. Harper hit 22 homers with a .270/.340/.477 slash line. Soto posted a .406 OBP. Griffey slashed .264/.329/.420 with 16 homers and 16 steals.

If Griffin is a true superstar talent, perhaps those ought to be his select comps. Harper and Griffey were No. 1 overall picks in the Draft and viewed as generational prospects. Soto was an uber prospect. Many are pinning similar lofty projections on Griffin.

If we assume Griffin is more like those names as a No. 1 prospect -- he's certainly an elite athlete, having even featured on "You Got Mossed" as a ninth grader -- then he could potentially be an impact player right now. And he does not even have to be a star to help the Pirates in his first season. If he's a league-average bat at shortstop, he would be a major impact player for the club -- as it would be for most clubs in the league.

While the Pirates have upgraded their lineup, they produced just one above-average qualified hitter last season. Griffin might be one of their very best hitters right now.

But what gets really exciting is Year 2, and perhaps getting to Year 2 as quickly as possible. For players debuting as teenagers since 1986, and who played in the following year, they increased their OPS+ on average of 18 points -- or nearly a 20% improvement.

(Note: The analysis of sophomore seasons did not include B.J. Upton and Wilson Betemit, who did not play in the Majors as 20-year-olds after debuting as 19-year-olds. Nor does it include Karim Garcia, who logged one plate appearance in the following campaign.)

Those who reached at least 200 plate appearances in their second season averaged a 106 OPS+, mostly as 20-year-olds.

Harper (133 OPS+), Soto (142 OPS+) and Griffey (136 OPS+) did much better than that and posted some of the best 20-year-old seasons on record. After struggling as a 19-year-old, Mike Trout went on to have the best season ever in terms of WAR (10.2) by a 20-year-old in 2012, elevating to a superstar level of play he would sustain for the remainder of the decade.

It raises the question of whether rare talents should spend more time in the Minors to refine their abilities and reduce the chance of severe struggles. Or, should they be thrown in the deep end that is facing Major League pitching and work through any adjustment period while in the bigs.

If Griffin debuted on Opening Day, he wouldn't quite arrive as quickly as Robin Yount, who made it up after only 64 Minor League games, after being drafted out of high school by the Brewers as a teenager in 1973. He made the Opening Day roster in 1974 to begin a Hall of Famer career. Griffin's arrival wouldn't be that fast, but it would be a blur of a journey to the Major League level.

Griffin has totaled only 563 plate appearances as a professional, including none in Triple-A and just 98 in Double-A. An Opening Day assignment seems aggressive. But in speaking to one assistant general manager, his preference for an elite prospect is the latter path, the more aggressive approach.

"They are best developed when they see the most challenging pitching they can," the assistant GM said. "They tell us when it’s time to go up. Defense and [fundamentals] can be learned at any level. I don’t think it is prudent to keep them in the Minors unchallenged. I think that is not developing a guy."

After all, how can one truly get better against Major League pitching if they are not facing Major League pitching? All top prospects are eventually going to have to do that, so why not start the process?

Perhaps it also accelerates their development. Harper's best season came when he was 22, in 2015, when he won the NL MVP after bashing a career-high 42 homers. In his third season, Griffey was a 7-WAR player. Soto produced a career-best 202 OPS+ in his third year, albeit the COVID-shortened 2020 campaign. Those three were full-fledged superstars by 22, and perhaps that doesn't happen without accelerating timetables and development at the big league level.

But there are differing viewpoints.

"It feels like the [Prospect Promotion Incentive (PPI)] stuff has changed the attitude from, 'Keep him down for a bit and make sure they never go back,' to 'Let’s see if he can hang, and if not, we send him down,'" said another assistant GM. "I think the hype for these young guys like [Jackson] Holliday and [Anthony] Volpe can sometimes be a bit much and people expect too much at a young age.

"I’d probably lean toward a bit more Minor League time to expose any flaws."

There's another development to consider, too. Baseball America's J.J. Cooper recently documented that players who reach the Majors are spending less time in the Minors first. That's in part because there's a heavier college lean in Drafts and in part because affiliate counts have been reduced, but it’s also tied to development advancements.

The game has changed a lot in recent years. One can argue it's changed more in the last decade than it had in the previous 50 years preceding it due to new technology, data and training practices that have accelerated player development, not just at the professional level but also in the amateur game. For instance, advanced pitching machines and simulators, in addition to new training regimens -- like bat speed and bat-path training -- can accelerate development.

Regardless of whether a prospect is pushed, every player who arrives to the Majors will face a sink-or-swing moment to see if they can stick.

Griffin's arrival appears like it will come sooner rather than later. And perhaps the sooner he debuts, the more that will accelerate him toward a star-level production.

At some point, Paul Skenes could be opening a playoff series for the Pirates, and Griffin could be hitting near the top of the lineup. The vibes have rarely been this strong this time of year in Bradenton, Fla.