A little more than four years ago, on the cusp of the 2014 big-league baseball season, you could have been forgiven for not paying all that much attention to Eddie Rosario. His performance as a 21-year-old between High-A and Double-A in 2013 had been good but not exceptional (a .275/.324/.415 line over 746 plate appearances), and he’d just been popped for use of a banned substance, which would keep him off the field for the first 50 games of 2014. He was a back-end top-100 prospect — No. 60 on BP’s list, 76 on ours, and 119 on Minor League Ball’s — but sufficiently outclassed by the four Twins ranked above him on all three lists (Byron Buxton at No. 1 on our list, Miguel Sano at No. 10, Alex Meyer at No. 23, and Kohl Stewart at No. 32) that he missed out on much of the national attention then showered on his colleagues.

Four years later, it’s a different story in Minnesota. Stewart is in Double-A, Meyer is in Anaheim, and Rosario’s 9.0 career WAR outclasses every single one of the Twins’ prospects from that loaded class, including Sano and Buxton — even if you throw the rest of our 2014 Twins top-10 list into the hopper for comparison’s sake:

Now, let’s be clear about what I’m not saying here: I’m not saying that Rosario will end his career with more WAR than Buxton, Sano, or even Berrios, who’s had a pretty nice start in the majors, as well. At 25, Rosario is older than all three of those men, and more than a third of his career WAR has come in the last three months. We’re nowhere near being able to render a final verdict on the Twins prospects of recent vintage. So I’m not saying Rosario has “won” anything or that his peers have flopped.

What I am saying, though, is that it’s perhaps at least a little surprising that Rosario — and not any of the other men on this list — has been the most productive member of that loaded Twins farm system to date and, further, that perhaps his performance to date merits a little bit of examination as a result. So let’s examine, shall we?

When Rosario came up, the knock against him was that he was somewhat too inclined to chase pitches out of the zone, relying on strong wrists and quick reflexes to get to pitches he had no business getting to and ending, all too often, plate appearances with singles on pitches out of the zone that he probably should have extended until he got a better pitch to hit. That report held up for most of Rosario’s first three years in the big leagues. It hasn’t been quite as true this year, though. Rosario is still a likely candidate to swing outside of the zone (his 78.5% offer rate out of the zone is lower than only seven other qualified players), but he’s gotten far better at understanding when expanding makes sense and when to hold back. Compare, for example, his swing rate with two strikes before 2018 (top) and so far this year (bottom):

That new discipline with two strikes has resulted in significant improvements in Rosario’s outcomes in, for example, 0-2 counts. In those situations, his wRC+ is up to 115 (up from last year’s 12, and far higher than 2016’s career-high of 69). His strikeout percentage is just 25.4% (down from last year’s 40% and, again, well below his career high). And, perhaps most impressively, he’s doubled his rate of hard contact, from 24.1% last year to 54.5% this year. Down in the count, 2018 Rosario is a different hitter than he’s ever been, and a better one — all while remaining one of baseball’s elite bad-ball hitters in all other situations.

And Rosario’s adjustments this year haven’t been limited to 0-2 counts. He’s also become far more willing to pull the ball in the air, with an attendant — and dramatic — increase in power. Before this season, Rosario was about as likely to go up the middle as he was to turn on an inside pitch and pull the ball in the air down the line. That’s no longer true: his pull rate has jumped (to 45.8% from last year’s 39.3% mark) by just about the same amount as his fly-ball rate (which has leaped to 45% from last year’s 37.4%). Together, those changes have made a difference. Rosario has hit 17 home runs already this season — last year, he didn’t hit his 17th until August 20th — and just two of those have been to the opposite field. (By comparison, 21 of his 50 previous career home runs came to the opposite field.)

That shift is partly, probably, a change in swing path, but it’s also likely a change in pitch selection that mirrors some of the improvements in two-strike approach we’ve already discussed, and it suggests a burgeoning maturity in approach for a player now in his fourth big-league season. Last year, Rosario hit fly balls on pitches all across the zone, and even about a third of the time on pitches up in the zone. This year, most of Rosario’s fly balls have come on pitches down in the zone that he can effectively get under and pull down the line. That’s not necessarily something you want to see a player get too happy doing — the league will adjust, after all — but it appears to be working for Rosario so far.

That is a pretty good summary of Rosario’s position relative to the other Twins of the 2014 draft class, as well. Buxton is still a far more talented athlete than Rosario could ever hope to be, and there may yet be time for Sano to rescue his career from the morass that has been his 2018 season and develop into a better big-league hitter. Both men could end up in front of Rosario on the career WAR lists when all is said and done. But nothing says “can succeed as a big leaguer” like having done it. For now, Rosario has found an approach that’s working for him, and he’s out in front of the pack at the quarter-mile mark. So far, at least, Eddie Rosario has surpassed his peers.