We Don’t Really Know How Giancarlo Stanton Will Age

In the midst of a slow beginning to the offseason, the big slugger in Miami keeps hitting homers — at least when it comes to providing content. Even after I made the case for acquiring Giancarlo Stanton — particularly for a team like the Giants — and Craig Edwards pointed out how an opt-out lowers Stanton’s value, the NL MVP remains a source of inspiration. Because, while all of those posts regarding Stanton feature assumptions about his ability to produce years from now, none of them focus on how well or poorly he’ll age, specifically. How he ages, though, is super important to how one thinks about his contract. It’s a matter worth unpacking further, in other words.

Before we slice up the data to identify players comparable to Stanton, I thought it might just be interesting to look at the players who have aged the best and the worst since free agency began in 1974. To do this, I simply found all qualified players’ win totals before age 27 and compared those figures to their work after they turned that age.

The approach has some shortcomings that become more clear as you look at the players on the list, but it’s sufficient at least to sort players into two buckets. After removing active players, I took the top 35 by each sort to represent my worst and best agers. They represent the extremes, the top 5% in each case.

I wanted to see if any metrics specifically might reveal how these players age, so I used walk rate, strikeout rate, isolated slugging percentage, baserunning runs, and defensive runs to evaluate the two groups. I thought it would also be interesting to see how big and tall each group was, and how many games they averaged per full season going into their age-28 campaign.

Here are the two groups. And Giancarlo Stanton.

Maybe the most remarkable thing about this form of analysis is how similar the two groups are. Both groups had above-average patience, contact, baserunning, defense, and power. There are a few differences, but they run counter to what you might expect, and don’t provide a good roadmap when it comes to Stanton.

Do the good agers have a better sense of the zone? They walk more! Stanton walks more. The good agers didn’t rely on power as much, though. Stanton’s best foot forward is his power. Is that bad? And while Stanton is no lumbering slouch, his speed and defense numbers don’t age up to either group… and it’s the bad agers who had better power and defense.

One thing you’ll notice as you go through the names on either list — here for your benefit — is that the poor agers often didn’t get a running start on their career. The fact that guys like David Ortiz, Jorge Posada, and Gary Sheffield had some trouble as younger player helped them by this analysis by suppressing their early career totals.

We could limit the pool to people more like Stanton, as much as that will kill the sample. Stanton is 14th among players since 1974 who had 4,000 plate appearances before they turned 28. Let’s look at the best agers in this bracket. Now we only have 53 in our sample, and we have to include active players or we’d really lose our comps.

Now the tide turns against Stanton. Better agers among players with 4,000 plate appearances before they turned 28 were shorter, lighter, played more games per season, made more contact, and relied less on power. But our sample of thousands has been reduced to 54, of which a good portion are still playing and can change the math on their particular baseball card.

And this is the problem with aging and comps in general. We can say, as Jeff Zimmerman has shown, that heavier players have aged poorly in the past, but do we know if that differentiates between the Adam Dunns and Pablo Sandovals of the world? Cal Ripken was once too big for his position, and he’s on our good list. Barry Bonds… well, now there’s another confounding factor when we try to analyze this sort of thing.

When you try to figure out how Stanton will age, there are as many different ways to attack the question as there are players out on the field, in a way. And while assigning each of his outcomes a likelihood is critical to how you much you want your team to go get him, it’s still a guessing game. Is he Paul O’Neill? Or Tom Brunansky?