Best of BP: Reflecting on Rookie Hitters

Image credit: Philip G. Pavely-USA TODAY Sports

An inherent part to writing the Stash List is trying to figure out how to value rookies, because in most leagues they aren’t rostered or even available until the big league club calls them. It’s also like being told we can finally reach for the marshmallow in an experiment, which is thrilling whether we get a second reward or not. But for as much data that we have today that’s publicly available, it’s still hard to see what, exactly, is coming, because it’s not all available for minor leaguers. 

Tempering our optimism might create enough pause that we miss on a difference maker (Michael Harris II), while being thrilled someone else is up as early as possible can cause us to crash and burn (Spencer Torkelson). There are examples from any year you choose who may more readily jump to the front of your mind for how they scarred your heart. The point is the same, though: Getting it right is hard, whether it comes to drafting or stashing rookies. 

This year’s rookie hitter class has felt a bit different. There really was a player type for you no matter your preference, from high profile international signing (Seiya Suzuki) to polished college bat (Steven Kwan) to budding developmental success (Lars Nootbaar). There were others filling additional roles, like the high-minors dude who raked (Jose Miranda), to the #gritty utility guy (Brendan Donovan), to the top prospect we’d been waiting for all along (Adley Rustchman, Vinnie Pasquantino). Of course, there was also the top prospect we got right away who worked out (Julio Rodríguez) and the in-season call-up who went bonkers from jump street, even if we thought it wouldn’t happen until at least a few years from now (Harris). 

By and large, the list each week doesn’t eschew context, but it doesn’t exactly prioritize it. Since the season is winding down, we’ve got the space to build some now, though. The following chart provides league-average wOBA for qualified rookies and then the league at large over the last 10 full seasons. I know that wOBA isn’t everything, especially since it doesn’t incorporate steals. However, the new rules could make that a moot point, and wOBA does give us a proxy for what the average rookie is compared to the average big leaguer.

Generally speaking, debut players will come in about 20 points off the league average, give or take a few points in either direction for a given year. One thing worth acknowledging is how rookies have held their own, relatively speaking, when it comes to generating offense the last couple seasons even as the major league average slipped. There have also been more debuts by qualified plate appearances in each of the last three full seasons than we saw in any of the previous seven (or eight, if you’d like to include the 2020 season). 

So, sure, we could argue the young folks have turned up the volume and had louder debuts, but that still doesn’t get to the heart of how this year’s crop has performed because their performance has still checked in below average. Here’s another chart, this time giving the range of wOBA among the top 15 qualified rookies for each of the last 10 full seasons. 

We’re working with the top 15 rookies here because of how that number fits the scope of a 15-team league. Here is the most noteworthy detail: This year has given us the smallest gap in wOBA between the best rookies since 2015, suggesting a high and consistent quality. How that quality plays in the future is up for debate — the 2015 class gave us Kris Bryant, Kyle Schwarber, Carlos Correa, Michael Conforto, and Francisco Lindor, but it also gave us Miguel Sano, Greg Bird, Devon Travis, Jason Rogers, and Randal Grichuk before he turned into mostly a defense-first guy whose fringe-average bat isn’t terribly useful in fantasy. The bigger point is that there’s something worth paying attention to with this bunch.

Here’s the catch, though: the top 15 rookies by wOBA this season are not who we thought they’d be. The group excludes Bobby Witt Jr, Riley Greene, Oneil Cruz, MJ Melendez, and Nolan Gorman. All five of those guys had helium coming into the year, and, at best, have only risen to it recently. The top 15 also excludes early season breakouts Christopher Morel, who has cooled off considerably since the early part of the year, and Juan Yepez, whose positional inflexibility and limited (if real) skill set might make him the odd man out in St. Louis, if it hasn’t already. As a group, the best rookies this year have been both 1) better than we might have expected and 2) definitely not who we expected. Depending on how much you invested in one of those guys who ended up being a miss, it very likely got in the way of adding one of the surprise hits.

So, there are two questions. The first: What’s worth tweaking about how we evaluate rookie hitters?

For me, I’m going to take a look at future rookie pools with a wider lens. That’s a deliberate visual. It’s not about taking in more information and trying to squeeze it into the same scope. Like loading a penny with drops of water, it would eventually spill out and I’d have a small, tedious mess. It’s also not about finding a stat that acts as a silver bullet, though I’ll still use things like chase rate and other contact data that drips out in the news as shorthand to grok a player’s skill set. 

Overall, a wider lens is about setting up a more spacious vantage point so I can see additional guys coming over the horizon. I’m going to be a little more interested in skill jumps (Nootbaar) and weigh step-by-step level progression (Greene) a little less. I’m going to believe a team’s actions with their depth chart more than buzz about a guy off it (Atlanta, St. Louis). I’m not going to be as concerned with sample size before adding a guy (say, Vaughn Grissom) because sample size is far more useful in the big picture than in individual cases.

And here’s the other question: Where do you slot them in, whether on an actual list or in your brain, when it comes being ready to draft or stash them? 

My answer starts with another question: What point of the season is it? 

If it’s earlier, including draft season, the allure will be at its strongest but it will also make the least sense. Strategizing around a rookie as an essential cog is like building in the dark. Investing in a guy earlier also implies a bigger commitment, because you wouldn’t be investing  if you didn’t want them to turn out good enough to keep all season. But the longer the season goes on, more will have become concrete around my teams and leagues. I’ll have a sense of where my deficiencies actually are and how I stack up with the teams ahead of me. And if I’m really on it, then I can invest in guys before their production gets too loud to ignore, before we’re writing about them multiple times over the course of multiple weeks, which also takes pressure off needing him to work out. 

More than anything, I suppose, I’ll be trying to calmly balance as many of these things as possible. It’s so easy to confuse enthusiasm for a player with buying into what they’re doing, even though they aren’t close to being equally helpful.