It seems lately that the Boston Red Sox have had a quite a few rookies come up to the majors and disappoint. Some claim that this is because the gap between the minors and majors is larger than ever, while others suggest that the Red Sox are rushing their players through the system. Damian Dydyn and Ian York look to answer the question: Are rookies having a harder time adjusting to the big leagues than ever before?
The Red Sox have seen a number of highly-touted rookies who have struggled in their introduction to the major leagues. Will Middlebrooks, Ryan Lavarnway, Jackie Bradley Jr., and Xander Bogaerts are all recent examples of Boston rookies who came up with lofty expectations, only to disappoint.
Rookies struggle. It’s rare for a player to immediately achieve his full potential as soon as he is promoted to the big leagues. When a team is under the media spotlight, like the Red Sox, and rookie expectations are magnified, it becomes even harder for rookies to meet those expectations. But with most of the Red Sox recent rookies failing to meet expectations, is there something more going on?
John Farrell, as quoted by Peter Gammons, said in 2014 that “the gap between Triple-A and the Majors may be wider than it’s ever been”. In an article by Brian McPherson, in the Providence Journal, Ben Cherington has suggested that they need to perform an “informal recalibration” of expectations for young hitters entering the major leagues.
On the other hand, Cherington has also acknowledged that the Red Sox have been aggressive about rushing rookies to the big leagues. In an interview with Peter Abraham, in the Boston Globe, Cherington said “we’ve probably moved some guys quicker due to circumstance. Looking back on it, is there is something we could have done differently? Yeah, maybe.”
Is it true that the gap between triple-A and the majors is wider than ever? Have rookies in general had a harder time adjusting to the big leagues in the past few years, perhaps because the major league strike zone differs from that in the minors? Or are the Red Sox unusual in their rookie woes?
We looked at rookies over the past 25 years, to see how well they have performed historically and recently. In order to gather data, the decision had to be made on which rookies to include. Those who came up for a cup of coffee and had two plate appearances are not the ideal population. On the other hand, if the plate appearance bar is set too high, then the data will include only those rookies who were good enough to stick in the major leagues for most of a season. To counter these problems, two cutoffs were used: The first season in which a player had enough PA (502) to qualify for batting titles and those who had a third of that number (167 PA), to look at those who played at least a couple of months in the majors during their first season. (We also looked at true rookies – players who reached those cutoffs in their debut season. The results are essentially identical to those shown here.)
Here are the numbers of rookies who qualified for each cutoff since 1990:
In both cases, at first glance, it looks as if the suggestion is right, since rookie OPS over time has been moderately decreasing since the mid-2000s:
However, that is misleading – in that period, offense has dramatically declined across all of baseball, not just for rookies. A better comparison is to look at wRC+, which normalizes performance to league averages. With this adjustment, there is no evidence of a recent decline:
Although the latest year shows a lower mean wRC+ for rookies, this isn’t a trend, and other years over the past 25 years have had equally poor showings by rookies: 2009, and almost all the 1990s, had similar or lower wRC+ showings from this group. It may be technically true that most of the 2000s had a higher mean wRC+ for rookies, but the difference is very small, and the outliers are just as common and just as low.
In the past few years, we have seen the arrival of rookies like Mike Trout, Bryce Harper, and Wil Myers, who broke into the big leagues as very effective players. If top prospects’ performance was worse recently it might skew the perception, since most media attention focuses on them. We looked at performance of the top ten prospects of each year since 1990, in the first year in which they reached 167 PA. We also looked at the pool of players left over after removing the top prospects:
It is true that the top prospects who broke into baseball in 2014 (Oscar Taveras, Javier Baez, Xander Bogaerts, and Gregory Polanco) were relatively disappointing in their debut. But the bulk of rookies that year, and top prospects over the previous years, performed pretty much to historical expectations.
Finally, what about the average age of rookies at their debut? Players have been making their debut at older ages since the 1960s. This may suggest that rookies really are having a harder time breaking into the big leagues, and therefore need more time in the minors to adapt to the more difficult game. However, this trend has slowed down or even nearly stopped since the late 1990s:
Objectively, it is hard to find clear evidence that Cherington and Farrell are correct about rookies having a harder time breaking into the big leagues in recent years. While their absolute offensive numbers are down since the mid-2000s, the same is true for veterans. There is no sign of a relative decrease by rookies compared to veterans. There are year-to-year fluctuations in wRC+, usually fairly minor, but no sign of a significant trend. It seems that in this case, the poor rookie performance may be a sign that, whether due to misjudgement, over-aggressiveness, or the force of circumstance, the Red Sox may have brought some of their rookies up earlier than they should have.