Are Rookies Having a Harder Time?

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:


Another way of looking at the same data is to use a boxplot, so that we can more easily see the mean wRC+ and the distribution:

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.

Follow Damian and Ian on Twitter @ddydyn and @iayork, respectively.

About Damian Dydyn 40 Articles
Damian grew up smack dab in the middle of Connecticut and was indoctrinated into the culture of Red Sox fandom from the moment he was old enough to start swinging a bat. A number of trips to Fenway park and meeting Ellis Burks at his dad's bar cemented what would become a life long obsession that would pay off in spades in both the recent run of post season success and the extra bit of connection he would have with his father throughout the years. After a brief three year stint living in the Bronx with his wife where he enjoyed leisurely strolls through the neighborhood with a Red Sox t-shirt on to provoke the natives, he settled in Roanoke, Virginia where he can fall out of bed and land at a Salem Red Sox game. Damian is a co-host for Sports & Sorts Shorts with Shane Moore, a baseball podcast covering Red Sox and Yankees topics.


  1. Seeme like there’s another plausible explanation different than the only one you list at the end there – and that would be that we overrate our prospects. I mean a guy like middlebrooks was a pretty mediocre milb hitter with pretty mediocre peripherals, aside from maybe one big year – doesn’t make more sens to note that he never really was all that good, rather than to blame the org for rushing a guy who had a good stint at every milb level and wasn’t that young for a rookie? bradley didn’t debut until age 24 – is it possible his milb numbers were inflated by being old for his levels? are we setting expectations too high already for a guy like swihart given his ordinary milb performance?

    You might want to do a follow up article comparing milb wrc+ to mlb wrc+ for prospects, I think.

    • I think we definitely tend to overrate prospects, especially our own and the sites that evaluate them aren’t immune to feeding this mindset either as it’s exciting to say something like “Player X has a ceiling of Albert Pujols” and will draw page clicks and discussion. It’s also an easy way to give a vague idea about a prospect without having to spend a ton of time in describing them.

      What we, as fans and consumers of that content, need to keep in mind is the likelihood of reaching that ceiling. It’s great if Xander Bogaerts has a ceiling of, say, Derek Jeter, but if his likelihood of reaching that ceiling is somewhere around 5% then throwing out that comparison, or expecting even a lite-version of him is probably going to lead to disappointment.

      We also need to relearn patience. A couple of decades ago, no one expected rookies to step in and be Mike Trout. These days we are very quick to throw the term “bust” around if players struggle early in their careers. Take JBJ for example. He’s not a bust yet. He still has plenty of time to carve out a really nice major league career. It might not be in Boston, but I’d be surprised if he doesn’t at least end up a valuable bench player, if not a solid starter down the road. Was he overrated? I’m not sure. I don’t recall reading much about his bat ever being more than adequate. It was always about his glove and the eyeball test seems to back up the idea that his glove is exceptional. All he really has to do is get that OBP up to around .330 and he’s a starter somewhere.

      • good points all, Derek. but i’ll disagree with you a bit on two things… in different directions.

        on the negative side, at age 25 Bradley is not young enough that we can afford him so much patience. he’s got to be good soon or else the bust label does become legit.

        on the positive side, imo my bar is much lower….in today’s game, a .330obp is excellent. average is closer to .310. A guy with bradley’s D (even if it’s not the generational D that too many crown him with too easily) can be valuable even with just a .300obp. Or in my favored wRC+ terms – get him to even 90wrc+ and he becomes a legit, if unspectacular, starter.

        • I don’t agree about him being too old to have any more patience with. Plenty of useful players break in at 26 or older. He’s going to need to start hitting major league pitching sooner rather than later, but I just can’t bring myself to label him as a bust yet. And I just don’t see an argument for him being old for his levels as he progressed through the ranks. I’m working on a piece now that touches on average age for the various levels of the minor leagues which should shed some light on that, but at 24, he hasn’t yet reached the average age for AAA players. In fact, he’s been below league average age for every level he’s played at since the start of the 2012 season.

          As for league average OBP, yes the MLB average last year was .314 and for center fielders it was .325 which are both lower than the .330 I mentioned. Those numbers, of course, include non-starters which brings them down a bit. For a starter, I would think .330 is a fair number, especially for a hitter like Bradley who doesn’t have much power and strikes out a fair amount. That number will fluctuate a bit as the offensive environment continues to shift.

          wRC+ is a great stat, though. I love it and use it quite a bit. It’s my go to stat for overall offensive value in most instances. Thanks for the comments!

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