The Home Run Derby won’t kill Mike Moustakas’s production

For those of us born after 1991, Monday’s Home Run Derby will be uncharted territory. It was 26 years ago that Danny Tartabull hammered precisely two home runs in the annual festival of might. Since then, no Royals hitter has participated in the event. I don’t know what it’s like to watch one of my hometown players in the greatest slugfest of the year. I don’t even know what it’s like to watch one of them stand there and hit zero home runs, like Robinson Cano*, a three-time participant and guy that absolutely nobody in Kansas City holds a grudge against.

*Every article about the Home Run Derby written in Kansas City is required to mention that Robinson Cano once hit zero home runs in a Home Run Derby.

It almost feels wrong. Mike Moustakas’s 25 home runs signify either that someone made a clerical error or that I’ve Rip Van Wrinkle’d three months away and it’s actually the end of September right now. Royals players almost never hit 25 home runs in a season. Certainly not before the All-Star break. This team won a championship by stubbornly doing anything but hit home runs. And two short years later, they have a player in the Home Run Derby.

A Royals player is finally on pace to break — shatter, even — Steve Balboni’s depressingly low single-season home run record. At his current pace, he’d hit between 46 and 47 home runs, more than ten beyond Balboni’s 36. He’s got this in the bag. There’s nothing that could stop him at this point. Only some sort of supernatural force could slow him down.

— some sort of… curse. Some sort of Home Run Derby curse.

The theory goes, roughly, that either participating in a Home Run Derby jacks up your swing or your back or what have you, or that the baseball gods hate such flashy displays of showmanship and want to see the participants fail.

But let’s be honest, this curse doesn’t have much teeth. If you Google “Home Run Derby curse,” all of the articles on the first page are about how the “Home Run Derby curse” isn’t a thing. The studies are all pretty clear - participating in a Home Run Derby has no bearing on how you perform in the second half of the season. And it’s pretty simple to crunch the numbers on this, so we might as well run a quick study of our own.

Let’s do the math.

First, let’s set some ground rules:

• We all should expect Moustakas (and everyone else) to hit fewer home runs in the second half of the season, because there are fewer games. We’re not worried about the total number of home runs he hits, we’re worried about the rate at which he hits them. So we’ll just use home runs per plate appearance (HR/PA) instead. Simple enough, right?
• We’re only concerned with home runs. Obviously, we want Moustakas to perform well in all phases of the game, but nobody claims that the Home Run Derby messes with your walk rate or how often you ground into double plays. Besides, in this case, I’m mostly concerned with Balboni’s record and whether Moose will be able to break it.
• We should expect the typical major league player to hit home runs at about the same rate in the first half and the second half. I already did the math on this. Over the last five years, players hit home runs at a rate 0.021% higher in the second half. For all intents and purposes, that’s zero.

OK, so let’s use the last five home run derbies and measure how their participants fared in the second half as compared to the first. I’m going to feed the numbers into this spreadsheet, and the next number we see will be how much, on average, their home run production changed from the first half to the second:

-23.7%

…oh. Home Run Derby participants typically lost about a quarter of their home run production after the all-star break. Everyone else was stable, but most of the derby guys tanked. That seems… bad? That seems bad.

But before you blame the Home Run Derby on this, make like Chris Berman and take a step back, back, back. Those players’ declines had nothing to do with whether they participated in the derby. For example, take a look at the 2013 derby.

That first column is each player’s career HR/PA up to, but not including, the year of the derby. This is the rate at which we expect them to hit, especially for the older guys.

The second column is the player’s HR/PA in the first half. The third is the same stat for the second half. (Oh, also, take a moment to remember that Robinson Cano finished last in this derby, too.)

Other than Prince Fielder (the defending champion) and David Wright (the hometown representative), everyone in the derby was absolutely crushing the ball in the first half. Chris Davis hit 37 home runs in the first half of 2013. Chris Davis broke Balboni’s record in the first half of the season. At that pace, he would’ve finished with about 63 dingers. You just can’t bank on that sort of production continuing through the second half.

Only two players from this derby saw their home run production increase: The champ, Yoenis Cespedes (who was pretty much in line with his career totals anyway) and Wright, who came into the derby hitting below his career rate. Everyone else saw their production regress downward to the mean, as could be expected.

And it’s important to note that the only player from this derby to miss significant time to injury was Wright. The Home Run Derby does not appear to cause any season-threatening injuries.

* * *

Most players are selected to the derby because they’re having the sorts of first halves that are outliers. Aaron Judge, for example, is not going to hit a billion home runs in the second half of the season. But I am still looking forward to watching him and Giancarlo Stanton murder baseballs.

And I’m still looking forward to watching Moustakas murder baseballs even though he’s also having an outlier of a season.

It’s reasonable to expect Moustakas to regress in the second half. And if and when he does, it won’t be the Home Run Derby’s fault.

If he does regress all the way back to his career averages, he’ll manage to fall just short of Balboni’s record, with about 34 home runs. I think he’s better than that. Remember, that career total covers some truly lean years for Moustakas.

If, however, his regression matches the average of Home Run Derby participants over the last five years — that scary 23.7% from earlier — he’d still manage to shatter the record by five home runs.

Somewhere between those two is the most likely outcome — a tight race with Balboni.

We can hope that Moose’s home run chase isn’t the only exciting part of September. For tonight, let’s enjoy watching Moustakas try to break Danny Tartabull’s franchise record of two derby homers. And then, when he returns to the K, let’s enjoy Moustakas’s personal home run derby for as long as it continues.