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Are the Yankees’ rookies due for a sophomore slump?

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What can recent history tell us about the Yankees’ rookies chances of avoiding the sophomore slump?

Boston Red Sox v New York Yankees Photo by Jim McIsaac/Getty Images

“As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know.”

Donald Rumsfeld brought the concept of the Johari window into public view, and it really is one of the best ways to analyze relationships, whether they be between a romantic couple or, in the case of this post, past rookies’ relationships with their future selves.

Miguel Andujar and Gleyber Torres had great rookie campaigns, that’s a known known. Both finished as Rookie of the Year finalists and played huge roles in lengthening a lineup that won 100 games. We know that their 2019s will be different, though we don’t know how different. And then there are the unknown unknowns - things we don’t see coming, and become very difficult to prepare for.

It’s that second category that I want to explore right now. How different will Andujar and Torres be in their sophomore years? It’s a pressing question, as with Manny Machado on the market and Didi Gregorius on the shelf, the expected performance of the two young infielders will drive a large part of the Yankees’ offseason strategy.

Steamer projects both players to take a step back, with Andujar pegged for a 114 wRC+ and Torres a 108, a drop of 14 and 12 points respectively. If I may quibble with a projection system for a moment, reading that made me question Steamer’s own process. Systems tend to project based on similar age groups, but not controlling for the relative ability of players at those age levels. Simply put, Rookie of the Year finalists should be better than most players in their age buckets, right?

That question drove me to look into whether the “sophomore slump” is lessened for the best rookies. It’s certainly real - despite excellent second seasons, both Aaron Judge and Gary Sanchez were a bit worse than their rookie campaigns, for example. But the best rookies, in theory, should be able to withstand regression better than the Tyler Austins of the world.

There have been 65 position players who have finished in the top three in Rookie of the Year voting between 2003-2017, in either league. Let’s see how they do in their second turn in the game:

So a sophomore slump is real, just like we thought. Total value drops by about 0.42 wins, and wRC+ declines by 12.5 points - almost exactly the average of Andy and Gleyber’s projected declines. As a percentage, that’s a 13% decrease year over year for fWAR, and 11% fall, YoY, in wRC+.

If we simply apply the above averages to the seasons of the five position players in each league’s finalist camp, this is what we can expect for 2019:

The important factor in this projection, though, is how wide the distribution is. The standard deviations for fWAR and wRC+ are 1.92 and 25.89 respectively, which incorporates a very broad range of possibilities. A two-win swing positively or negatively would take most players from either All-Stars to barely serviceable, and that swing in our set encompasses two-thirds of all players.

It’s also important to realize how many more players get far worse their second year than far better. 16 players in this set of 65 declined by two wins or more, while only six improved by two wins or more. The distribution of improve vs. decline was pretty even, with 51% of the set declining, but if you do take a step back, it tends to be a larger step back than you’re likely to take forward. This is why I’m so inherently skeptical that Miguel Andujar, for example, will continue to improve linearly. It just doesn’t happen historically, even for the best rookies.

To narrow this down to a single anecdote, Aaron Judge had arguably the best rookie season in baseball history in 2017. He was still fantastic come 2018, but his wRC+ dropped 32 points and he was worth 3.2 fewer wins. Even if you prorate his season to 650 plate appearances, reasonable for a guy that missed so much time with injury, his 2018 fWAR was “just” 6.52, a 20% drop from his rookie year. Guys just don’t get that much better in their second year.

The futures of Andujar and Torres are bright. Barring injury they should both have long and fruitful careers at the major league level. A probable step back in 2019 shouldn’t be a surprise though, as no player is really immune to regression. I hope, should both players decline somewhat, we can all stay positive and rational when it happens.