Mike Trout and Bryce Harper may have been joined at the hip last year, but there was no question that Trout was the better player. He was better than every player in the known universe, for that matter.
If it's batting numbers you want to go by, however, Harper is blowing Trout out of the water (sorry, had to say it). Harper's numbers say he's the one who still has room to grow, while Trout is the one who clearly peaked last year.
And this suggestion would be the truth of things, as we'll discuss in a moment. But first, how 'bout those batting numbers.
A year after hitting .270/.340/.477 with 22 homers in 139 games, Harper entered Wednesday's action hitting .312/.400/.633 with nine homers in only 31 games. He looks precisely like the kind of superstar hitter all of the pundits, in all their wisdom, said he would be.
As for Trout, he's not having a bad season with a batting line of .274/.342/.504 and five homers through 32 games. He's just not having the kind of oh-my-god-are-you-seeing-this season he had last year, when he hit .326/.399/.564 with 30 homers and 49 stolen bases.
A decline for Trout in 2013 always was in the cards, as it's not easy to maintain the kind of brilliance he showed last season, especially for a young player. As talented as Trout is, he managed to escape growing pains in 2012.
Inevitably, they have caught up with him this year. One of the ways you can tell is by looking at his key plate discipline data. Here it is, from Baseball Info Solutions by way of FanGraphs:
FanGraphs has definitions for these terms if you need them, but there are really only two things that need to be explained.
"O-" is referring to something done outside the strike zone. So O-Swing% is the percentage of pitches swung at outside the zone, and O-Contact percent is the percentage of outside-the-zone pitches a batter makes contact with. "Z-" is the opposite, as it refers to inside the strike zone.
Some regression stands out when looking at Trout's data. Most notably, he's swinging at more pitches outside the strike zone in 2013, and he's making significantly less contact when he does.
While Trout is making more contact in the zone this year, his O-Contact difficulties explain his overall drop in contact percentage. And that's not good, for making contact is, well, good.
This data doesn't say that Trout is overmatched, mind you. It just says he's not as perfect as he showed last year. As it turns out, he's quite vulnerable.
Now consider Harper's plate discipline data:
Harper is being more aggressive overall, and that's a good thing. He's being more aggressive within the strike zone rather than outside it, a la Trout. That Harper is making more contact on pitches both inside and outside the zone is a nice improvement, as is the fact that he's whiffing less.
I wouldn't say we're looking at a case of Harper going from being overmatched to being in control. The truth is that, for a 19-year-old player, Harper's approach last year was impressive. That it's gotten better this year is one of the overlooked signs that he was indeed born to play baseball.
But plate discipline data doesn't tell the whole story. It gives us a general picture of these guys' approaches at the plate, but it doesn't tell us how they're responding to how they're being pitched.
And to that end, Trout is being handed a major challenge this year.
I'm the last guy in the world who wants to take anything away from Trout's tremendous 2012 season, but there's one thing that must be noted: The kid got a lot of fastballs to hit.
Per Baseball Info Solutions by way of FanGraphs, Trout saw fastballs 64.7 percent of the time in 2012. For some perspective, only four players in baseball were fed fastballs more than him.
This may have had something to do with the book on Trout. His Baseball America scouting report (subscription required) noted that Double-A pitchers had success when they pounded him inside with fastballs.
Over at Baseball Prospectus, you can see how often Trout got fastballs on the inner part of the plate. Though not by a huge margin, he did see more inside fastballs than outside fastballs.
The strategy only worked to a degree. Trout's batting average zones from last year show quite a bit of hotness against inside fastballs.
Fastballs in general weren't such a good idea against Trout. Despite his late start to the season, he ranked 26th in MLB in wFB (fastball runs above average). Occasionally, he did terrible things to fastballs. Just watch this MLB.com video and then go ask Clay Buchholz.
So what's happening with Trout this year?
About what you would expect. The percentage of fastballs he's seeing has gone down from 64.7 to 59.6. The trade-off has been an increase in sliders, from 15.3 percent to 20.3 percent. In particular, he's seeing quite a few sliders on the outside from right-handed pitchers.
Such as the one from Yu Darvish here at the 17-second mark.
The fact that Trout is still having a good season goes to show that he hasn't been completely figured out yet, but it would appear that pitchers have found a weakness. That's a reminder that, as talented as Trout is, he's still a young hitter.
Harper's narrative, meanwhile, is almost the exact opposite.
Unlike Trout, Harper saw remarkably few fastballs in his rookie season. Only two hitters in the majors got fewer hard ones to hit: Alfonso Soriano and Josh Hamilton. Instead, he was fed a healthy diet of off-speed pitches and breaking balls. Pitchers were making him prove that he could hit major league pitching.
For the most part, obviously, Harper could. But when it came to curveballs, he was Pedro Cerrano.
Harper didn't like curveballs. He saw a lot of them and managed only a 1.6 wCB. For some perspective, the league-leader in that category was Matt Holliday, and he compiled a 13.2 wCB.
And boy oh boy did curveballs make Harper mad, as you can see in the video to your right.
Pitchers are going back to the well this year. Of all the hitters in baseball, only three are seeing more curveballs than Harper.
This year, though, he's been ready for them. After compiling only a 1.6 wCB last year, Harper already has a 1.7 wCB this season. There's still a lot of season left, but he's effectively taken away the best weapon pitchers had against him.
That's not the only thing that should worry pitchers about Harper. They should also be worried about the fact that his offseason weight gain seems to be making a difference.
Harper was one of the best 19-year-old home run hitters ever, as he fell only two homers shy of Tony Conigliaro's record for homers by a 19-year-old. Harper just wasn't the most efficient home run hitter, as he only had a 16.2 HR/FB rate that ranked 39th in MLB to go with his 32.9 fly-ball percentage.
Trout, by comparison, had a 21.6 HR/FB that ranked ninth in MLB despite the fact he had a modest fly-ball percentage of 33.0. Next to Harper and, well, almost everyone else, Trout was an extremely efficient home run hitter.
This is yet another area where the tables have turned.
Trout is hitting fewer fly balls this season, as his FB percent has gone down from 33.0 to 29.6. His HR/FB, meanwhile, has declined from 21.6 to 15.6. He's not being entirely inefficient, but he's certainly not as efficient as he was last year.
Then there's Harper, who has increased his FB percent from 32.9 to 36.0 and his HR/FB from 16.2 to 28.1. He's hitting the ball in the air more often, and it's going over the fence more often. That's what you want out of your best sluggers, and that's what Harper has become.
In Trout, we're dealing with a guy who had a brilliant year in 2012 and thus far isn't having a brilliant year in 2013. In and of itself, that's a big reason why it seems like he's plummeted back down to earth.
But there are other contributing factors to Trout's regression. His approach at the plate isn't as sharp as it was last year, and it doesn't help that pitchers are pitching him tougher. His HR/FB regression is fixable, but he may have a hard time getting back to where he was last year seeing as how he's more of a line-drive hitter than a home run hitter.
In Harper, we're dealing with someone who showed all sorts of promise for a guy his age in 2012 and who has built on that promise this year. He's tightened up his approach at the plate and done himself a huge favor by taking care of his curveball problem. In doing so, he's shown that he can adjust.
Beyond that, Harper's become the home run hitter that he was supposed to be all along and that Trout was masquerading as last year. Harper won't keep up his 48-homer pace, but going from 22 at the age of 19 to, say, 35 at the age of 20 would be an encouraging step forward.
What it all comes down to is this: We saw Trout's best last year, and now it's Harper's turn.
If you want to talk baseball, hit me up on Twitter.