Both are practically perfect hitters, and in practically identical ways. It's not just that they both hit the ball hard and far, but that they control the construction of each plate appearance:
Los Angeles Angels center fielder Trout has a phenomenal batting eye -- his chase rate is in the third percentile of qualified hitters. (Which means 97 percent of hitters swing at more pitches out of the zone.) Boston Red Sox right fielder Betts' chase rate is in the first percentile, basically indistinguishable.
Both are also patient when the pitch is in the strike zone: Betts is in the first percentile for swing rate, Trout in the third. The same.
Both rarely swing and miss. Betts' contact rate is in the league's 91st percentile, and Trout's in the 83rd.
And, according to FanGraphs, they've seen the exact same percentage of pitches in the strike zone. They, in fact, hover right around the league's median for zone percentage.
Put it together, and 56.6 percent of pitches Betts sees end up being strikes (or put in play), the third-lowest rate in baseball. And Trout: 57.6 percent, the fifth lowest.
So, they get the same number of pitches in the zone; they swing at the same number of pitches in the zone, and they chase the same number of pitches out of the zone; and when they swing, they make contact at the same rates. You'll identify those as the basic building blocks of a strikeout or a walk.
And yet, Trout has the highest unintentional walk rate in baseball; Betts ranks around 40th. (Intentional walks are excluded from all stats in this article.) And Betts has the 12th-lowest strikeout rate in baseball, while Trout is around 75th. Despite getting the same number of strikes, swinging at the same number of pitches, and making contact on the same number of swings, Trout walks 50 percent more often than Betts and strikes out 50 percent more often. What in the world?
The answers to this mystery show some of the nuances of how each player approaches a count, and how each player's count rhythm (to make up a phrase) can defy the broad generalities we draw about a player's approach from their overall plate discipline stats. (Trout takes more pitches with two strikes, for example; Betts chases more often with three balls.) More significantly, they show how much foul balls, of all dumb things, matter.
We don't pay much attention to foul balls. They're not a whiff, but they're also not a ball in play. In most counts they're bad (but not too bad), but in two-strike counts they're good (but not too good). Some travel 500 feet; some are detectable only by sound. You can stare at a foul ball percentage leaderboard and struggle to find any pattern.
But Trout is a major foul ball hitter. Of all qualified hitters this year, only two have fouled off a higher percentage of pitches per swing. Betts is a major foul ball avoider, down around the 25th percentile of fouls per swing. In the case of these two elite hitters, these foul balls create a huge shift in outcomes. Trout and Betts are just as likely to swing at, for example, any 1-0 pitch, but Betts is 60 percent more likely to put the pitch in play, because Trout fouls off so many of those pitches.
It's hard to say whether these different rates represent a deliberate approach by each hitter or merely the subtle differences in their hitting skills and styles. The "deliberate approach" hypothesis draws some evidence from foul ball rates per count: Trout's foul ball "edge" over Betts is especially high in early hitter's counts, like 1-0, 2-0 and 2-1. Betts' foul ball rates go way up with two strikes, when a foul ball gets the batter a new pitch, while Trout's stays steady throughout the count.
But regardless of whether these rates show intent, they do illustrate two different philosophies about count leverage.
The Betts philosophy (again, whether or not intentional) is that, in this era and with the strength of these hitters, there's a tremendous value to simply putting a fair ball in play, and a tremendous penalty to reaching two strikes.
We can see this striking trend in a stat called tOPS+, which measures the league's performance in one split relative to its performance overall. The league's tOPS+ with two strikes is 43 this year, which is a way of saying that its OPS with two strikes is just 43 percent of its OPS in all counts.
That 43 figure is the lowest since at least 1988, when count data began to be recorded. The second-lowest tOPS+ on two strikes came in 2017. The third lowest came in 2016, and the fourth lowest came the year before that. Modern pitchers are pitching for strikeouts, and they're really good at getting strikeouts, and so there has never been a worse time to hit with two strikes.
Now compare that to every other count:
With the batter ahead in the count, the league's tOPS+ this year is the highest on record. The next two highest were last year and 2016.
On the first pitch, the league's tOPS+ this year is the highest on record. The next highest seasons were last year, 2016 and 2012.
On 1-1, the three best seasons are the past three.
On 0-1, three of the four highest came in the past three years.
And on balls hit fair -- anywhere fair, from a bunt to a dinger -- the league's three best seasons have come in the past three years. (Betts hits .395 when he hits a ball fair, and slugs .780; Trout hits .410 and slugs .828.) To the degree that offense has survived the strikeout era, it's because batters today do a ton of damage when they hit it. To the degree that pitching has survived the new juiced ball era, it's because pitchers dominate when they get to two strikes.
So Betts' ability to avoid foul balls -- to actually put the ball in play, especially earlier in counts -- is really about his ability to avoid reaching that point in the at-bat when he gets to two strikes. Only 22 percent of Betts' plate appearances have ended in pitchers' counts, the lowest rate in baseball. (Trout: 27 percent.) And 50 percent have ended in hitters' counts, the highest rate in baseball. (Trout: 42 percent.)
By putting the ball in play, he's avoiding strikeouts. He's also not chasing walks: On 3-2 counts, Betts swings at almost 80 percent of pitches, compared to 54 percent for Trout. He does still walk a fair amount -- walks are always positive -- but the relative value of a walk is diminished when the ball is flying out to left field.
So the Betts foul ball philosophy is simple: Two strikes are bad, so don't get two strikes; hit balls are good, so hit the ball.
The other philosophy, though, sees that Trout (like Betts) is not a normal hitter. Pitchers are dominating the league with two strikes like never before, but that's because most batters swing and miss a lot. Trout and Betts don't. Trout and Betts don't swing through pitches in the strike zone like normal hitters, and they don't chase pitches out of the strike zone like normal hitters.
Indeed, Betts and Trout this year have been two of the best two-strike hitters we've ever seen. Trout is hitting .232/.338/.554 after reaching an 0-2 count -- that's basically Bryce Harper's career OPS overall. Trout's OPS in all two-strike counts is 227 points higher than the league average with two strikes, and the 34th best (minimum 150 two-strike plate appearances) since 1988. Betts' two-strike numbers are otherworldly: This year he has been arguably the best two-strike hitter in history, with a .328/.401/.634 slash line that is better (relative to the league) than anybody on record. It's a dead certainty Betts won't keep that slash line up forever, but both hitters' performances demonstrate the obvious point that good contact rates and exceptional eyes blunt the pitchers' two-strike advantage.
Trout (and even Betts) would prefer not to get to two strikes -- a foul ball really does put him in less advantageous counts -- but the reward for a deep count is a potential walk. Strikeouts are up across baseball, but so too are walks. Because Trout doesn't chase pitches out of the strike zone, he's much more likely to cash in those deep counts for free passes. And you can't make an out on a walk.
Imagine it this way: Say a pitcher throws a first-pitch fastball just off the edge of the strike zone. One hitter takes it for ball one, and another swings and misses for strike one. We know that makes a big difference: The league has a .381 on-base percentage after getting ahead 1-0, and a .261 OBP after falling behind 0-1.
But the stakes of a single pitch go up the deeper you get into a count, the closer to the sport's three-strikes/four-balls endpoints. The same pitch on 1-1 would change the expected OBPs to .388 and .225; the same pitch on 3-2 would change the expected OBPs to 1.000 and .000. In a deep count era, the man who controls the strike zone is king.
The net result: Betts' ability to avoid foul balls helps him avoid two strikes, the perfect strategy for this era. Trout's ability to hit foul balls helps him work deep counts, during which his ability to avoid strikes has the highest payoff, also the perfect strategy for this era.
Which hitter's foul ball philosophy is better? I'm not sure either one. The thing is, when you don't swing at pitches outside the zone, when you rarely swing and miss at anything, and when everything you hit goes far, there's not really a wrong way to make offense. Each of these hitters has found a way that works for him. The difference is subtle, but it's personal, and it's producing two historic seasons.