I feel like there hasn’t been nearly enough fanfare that we’re witnessing not just one amazing rookie campaign, but two in the National League East. Ronald Acuna was perhaps the most anticipated prospect to make his debut this season, while Juan Soto was decidedly less so. Although clearly a strong prospect, I admittedly never even heard of the guy. Maybe because each of them opened the season in the minors and have accrued just over 300 plate appearances, which is essentially half a season, you might not realize how incredible they have performed offensively. Their owners are certainly smiling ear to ear, but the more important question is which we should prefer to own next year. Obviously, we still have over a month of the season left and things could change. But let’s take an early stab at answering the question.
First, a comparison:
We’ll begin with basic plate discipline stats without diving deeply into the Swing% and Contact% marks. In the minors, Acuna’s walk rate oscillated up and down, hitting double digits in his first two seasons through Single-A, before declining into the mid-to-high single digits at three stops in 2017, and then rising back into the low double digits during his short stint at Triple-A before his promotion this year. His current walk rate is probably around what you would expect given his minor league marks, but he’s shown patience before, providing optimism that he could raise that rate pretty quickly. For now, though, it’s a bit below the league average.
On the other hand, Soto had posted double digit walk rates at five of seven minor league stops, though he really shot through the system, so just one of those stops resulted in more than 100 plate appearances. So it appeared that Soto possessed a bit more patience than Acuna. However, no one could have possibly predicted this. A 17.3% walk rate…AS A 19 YEAR OLD?!?!?! Are you kidding me? If he qualified for the leaderboard, he would rank third in baseball behind the best player in baseball, Mike Trout (a 20.5% walk rate, my gosh), and the Canadian God of Walks, Joey Votto.
While most leagues don’t directly count walks and only some leagues use OBP instead of average, in which walks directly contribute, a higher walk rate means more times on base, which means more opportunities to swipe a base and more chances to score a run. So point in Soto’s favor.
Next, the two have very different strikeout rates. Just once, At High-A in 2017, did Acuna really have strikeout issues, but everywhere else, he was at a perfectly acceptable level. Unfortunately, aside from that elevated mark at High-A, Acuna’s strikeout rate is the highest of his career, which isn’t a surprise when moving to the toughest level in the world. But, his SwStk% isn’t alarming at just above the league average, so this doesn’t appear to be a long-term concern.
Soto is once again impressing, as his strikeout rate is well below the league average and barely higher than his walk rate. In fact, he has only struck out five more times than he has walked. That’s fantastic in its own right, but again, as a 19-year-old, that’s just insane. That also comes along with a tiny 7.6% SwStk%. Given the power he has displayed to go with that low SwStk%, it’s just unfathomable that he’s doing all this…at the tender age of 19. Repeating his age can’t get old. So here, too, Soto has been better than Acuna.
From an overall plate discipline perspective, Soto is the clear winner. In my mind, that makes him a much safer bet to maintain a high level of performance (though I can’t recall a study that compared good plate discipline season to mediocre or bad ones to determine which type of players maintained their performance the next season better).
Now we turn to home run power, as measured by HR/FB rate. I included my xHR/FB equation so we don’t just take the HR/FB rates at face value. While it’s not shown in the table, both have been well above average in average fly ball distance according to Statcast, while Soto has been notably higher than Acuna. Interestingly, a higher rate of Acuna’s fly balls have been classified as barrels, though again, both are well above average. The real head-scratcher is each hitter’s fly ball pull rate. Acuna is about league average, while Soto has been painfully averse to pulling his flies. I don’t know where he would currently rank, but his 11.1% fly ball pull rate is about half the league average. The good news is there’s nowhere to go but up, giving him some upside. But it would seem to make his HR/FB rate a bit more difficult to sustain as it’s hard to hit the ball 350-400 feet the opposite way than it is to pull it that far.
Coincidentally, both sport the same HR/FB rate currently, with Acuna’s xHR/FB rate nearly matching his actual, while Soto’s is a bit below. Acuna hadn’t shown this type of home run power in the minors, so it appears he’s enjoying his power breakout now. This differs with Soto who enjoyed his power breakout in the minors this season before his recall and it has continued in the Majors. Acuna has high GamePower and RawPower scouting marks set before the season, so scouts clearly expected him to be the better power source. Now, I would probably lean toward Acuna as well, as Soto’s fly ball pull rate makes me a bit nervous if he doesn’t raise it.
Moving on to BABIP, we find that both have seemingly overperformed their underlying BABIP skills based on my xBABIP calculation. For a power hitter, Soto is strangely against hitting fly balls. Though that hurts his home run total, it actually helps his BABIP potential. Also helping is a low rate of pop-ups, power, and a touch of speed. Hurting him is a low LD%.
Acuna also sports a low LD%, but has more speed and has hit the ball harder. However, he has pulled grounders into the shift more often than Soto and has even been shifted more, even though he’s the righty and Soto the lefty. I’m sure he’ll get that LD% up, but he’s most certainly not a .350 BABIP guy.
Both hitters were typically big BABIP guys in the minors, so inflated marks have become their norm. It’s a close call on who to expect a higher BABIP from in the future, but I think I’ll bet on the right-hander with speed.
Speaking of speed, Acuna’s stolen base potential is what really made him an exciting fantasy prospect. The chance he goes 20/20 far exceeds the value of another random prospect who might hit 30 homers, but with no steals. This is what really separates him from Soto for fantasy.
Overall, given the plate discipline differences, I might lean toward Soto in real baseball as you just can’t fake that walk/strikeout rate combination. And at age 19 (once again, in case you forgot), it suggests a superstar career ahead. However, Acuna has the element of speed, and he’s only 20, so that speed shouldn’t fall off for at least several years. If we’re not totally sure who’s going to hit more homers between the two, and a slightly higher BABIP from Acuna offsets the worse strikeout rate, then the steals wins him the fantasy battle.