Rookie of the Year and the Mythical Sophomore Slump

Time to bust out your Kirt Manwaring Rated Rookie cards, kids. It's that time of year!

Rookie of the Year is a bit of a strange award. It's given, I presume, to the rookie-eligible player who had the most valuable season in each league. It has good historical pedigree, as Jackie Robinson won the inaugural award in 1947 (when there was only one RoY for both leagues). Nevertheless, it produces some odd results and gives a lot of weight to the perception of the "sophomore slump."

Consider this: after you adjust for the development curve and the salutary effects of experience, would you expect a random player chosen from the pool of first year players to be better than a random player chosen from the pool of ten year players?

Your first instinct might be to say that it shouldn't matter; after all, if we're adjusting for age then the average player is the average player. Except, as in the classic Monty Hall problem, my setup makes the second choice more attractive by providing the chooser with additional information. In this case, the ten year player has survived the ruthless selection that occurs at the major league level. As a result, a Good Bayesian should update his priors and select the veteran.

So what, you say. It doesn't matter that the award is given to an overall less deserving set of players. The point is to recognize the best newcomer to the league!

Well, I'm not sure that makes sense either.

Two objections apply. First, players enter the league at staggered points on their aging curves. So, players who are called up for partial seasons (eliminating rookie eligibility) are penalized, as are players who are called up at a young age. As a result, players like Alex Rodriguez, Barry Bonds, Tim Lincecum, Johan Santana, and many others never have a chance to win the award. Further, players who enter the league late in their careers, like Ryan Howard, have a systematic advantage.

The second objection is that it is more sensitive to year-to-year fluctuations than other awards because the rookie year tends to be the first impression voters have of a player. The best way to illustrate this problem is with an analogy.

How many times have your too-cool-for-school hipster friends decried a band's second album? "Sophomore slump" they proclaim, or "they sold out!" Or how about the entire directing career of M. Night Shyamalan. These artists make one good cultural artifact, and everyone assumes they're geniuses. Then, when they inevitably fail to match their previous level of success, it's because of some personal flaw.

Consider what Larry at Wezen-Ball has found:

In the first 50 years of its existence (from 1947 through 1996), there were exactly 100 awards handed out. Thirteen of those players are currently in the Hall of Fame (Cal Ripken was the last winner to be inducted). In addition to those thirteen, Pete Rose is ineligible for the Hall, Andre Dawson is inching his way towards induction, Mark McGwire is sitting in limbo, Jeff Bagwell & Mike Piazza are not yet eligible, and Derek Jeter is still playing. Counting all six of those players, that puts the HOF-success rate of the Rookie of the Year award at 19%. It increases to 20% if you consider Lou Whitaker and his 69.7 career WAR as a HOF-worthy player (Dick Allen's 61.2 career WAR also has a case). Since 1997, Rookie of the Year award winners have included Carlos Beltran, Albert Pujols, and Ichiro!, all of whom are likely Hall of Famers.

Fewer than 20% of RoY winners go on to make the Hall of Fame (don't get me started on Dick Allen, who never once in his life got a fair shake). Why could this be?

Call it the Shyamalan Effect. He made "The Sixth Sense," which everyone loved. But the acclaim the film received was partly because the reveal was novel, partly because it had (some) good acting, and partly because Shyamalan does have virtues as a director. But many of the reasons why "The Sixth Sense" was a success were entirely unrelated to Shyamalan. So when his subsequent films disappointed, it shouldn't have come as a surprise. (Note the convenience of the WOWY style of analysis: we can eliminate Bruce Willis as the cause!)

The same phenomenon holds in baseball. To some degree, success in a given season, rookie seasons included, depends on factors outside a player's control. I tend to think of all circumstances outside an individual's control as "luck," but if you choose a different word that is fine. The essential point is that other factors may combine in your favor or they may conspire against you. 

Because rookies are often unknown to the voters, they will select whichever one had the best performance in that one year. That is, their choice is unanchored by past performance, as it surely is in MVP consideration. So they are perhaps more likely to incorporate those contingent factors outside a player's control (team strength, for example, when looking at RBI, or defense, when looking at ERA) when determining whom to select.

I'm not suggesting the voters do a great job with the MVP or even that they do a particularly terrible job with the Rookie of the Year. But if Elvis Andrus collects his Rookie of the Year on the strength of his excellent defense and his .267/.329/.373 batting line with 33 SB, remember this. If we take away one hit a month and instead make it a walk, his line becomes .254/.329/.360 and he probably doesn't win the award. 

This phenomenon is compounded by the path dependency of expectations. A player who was a Rookie of the Year will be given repeated chances to prove himself. (What, you don't believe me?) By contrast, a player who underperforms in his first shot may not get another fair shot for many years. 

We've been spoiled by good Rookies of the Year in recent memory: Evan Longoria, Dustin Pedroia, Ryan Braun, and Hanley Ramirez are all poised to remain stars for several years. But the structure of the award still produces some bizarre results: Bob Hamelin? Marty Cordova? (On second thought, Hamelin's '94 might have been the last time a Royal slugged .599).

If you're searching for an explanation for why Angel Berroa won the award in 2003, remember that he was rewarded for contingent success as much as for inherent skill. And when this year's Rookie of the Year winners come back down to earth next season, remember that the only reason you thought they were breakout rookies was in part because they had good luck their rookie seasons.

I hope everyone who saw Unbreakable knows what I'm talking about.