Are the majors getting tougher for rookie hitters?

At times, last season felt particularly rough for young hitters just getting their feet wet.

There were problems in Boston, where, for example, neither Jackie Bradley nor Xander Bogaerts performed anywhere near the level of expectation. In St. Louis, the late Oscar Taveras had trouble getting into a groove and earning a regular job. Javier Baez mostly looked like a mess for Chicago, and for all the hype, Gregory Polanco eventually came up to join Pittsburgh and underwhelmed. Nick Castellanos was fine, but nothing revelatory. Billy Hamilton had a terrible second half. Jake Marisnick didn’t hit, and Jon Singleton didn’t hit, and so on and so forth. There’s nothing quite like top prospect hype, and there’s nothing quite like watching a top prospect struggle to hit at the highest level, after all the anticipation.

In each case, there was just anecdotal evidence, but put enough anecdotal evidence together, and you have a story. For at least several months, people have been discussing the theory that there’s a widening gap between the major leagues and everywhere else. Alex Speier is currently writing about this at the Boston Globe. There are reasons to believe this to be true; there are elements to playing in the majors that haven’t always been present. Most important, there’s more information than ever, so young players don’t show up as unknowns. Reports get generated, and reports get spread, and, faster than ever before, opponents are able to zone in on a given hitter’s weaknesses.

The feeling is that the majors have never been this hard for rookies. The feeling is that rookie hitters are facing an uphill battle, and hitting a baseball is no walk in the park even at the best of times, where you’re facing Kyle Davies in Colorado. There are feelings, and then there’s information. Let’s see what we can do with this. How have the majors lately been treating rookie bats?

This is going to be a post with graphs in it. The first graph shows rookie-hitter wOBA over the past 25 years. Note, firstly, that this is rookie non-pitchers. Note, secondly, that wOBA is just a statistical measure of offensive productivity, scaled to OBP. The higher the wOBA, the more productive the hitter. It shouldn’t be too hard to spot the trend here:

Look at that: sinking offense! The rookie wOBA last year was .291. That’s the low point in the whole window examined. But as you probably already picked up on, this is a little misleading because, well, I’ll just let the next graph make the point:

Offense has been sinking for everybody. You knew this; this is why the new commissioner is talking about things like getting rid of shifts and tightening the strike zone. Yeah, rookie offense is down. At the same time, non-rookie offense is down. So it’s hard to pin that on just the rookies.

This graph should be more helpful: instead of plotting wOBA, I’ve plotted wRC+. You might be more familiar with OPS+. The idea is the same thing. A league-average mark is 100. A number higher than 100 means the hitter was better than average. Here’s how rookies have done, year to year, relative to the changing environments:

Now that flattens things out some. Last year’s rookie wRC+ was 83. The average over the whole 25 years is 85, which is hardly any different. As recently as 2001, rookies posted an 80 wRC+; in 1996, there was an ephemeral drop into the 70s. For even more smoothing, we can examine rolling three-year averages. After all, it wouldn’t make sense for there to be a sudden change between 2013 and 2014, right? The most recent three-year average is an 85 wRC+. That’s exactly the 25-year average. While 2014 might’ve been relatively tough, in the end, 2013 was a little better, with the success of, say, Wil Myers, and Christian Yelich, and Jedd Gyorko. And rookies were even better the year before. Every season, teams are a little bit smarter, but it wouldn’t get unusually tough for rookies overnight.

There’s another little proxy we can use. You know what’s closely correlated to performance? Playing time. If someone is playing bad, he won’t play very much. So by examining rookie playing time, we might get a sense of relative organizational satisfaction, or dissatisfaction. In this graph, I’ve plotted rookie plate appearances expressed as a rate of total non-pitcher plate appearances:

Last year, rookies got 13 percent of plate appearances. The year before, 13 percent. The year before that, 13 percent. The average over the last 25 years: 13 percent. There was a strange three-year drop between 2000-2002, but maybe with performance-enhancing drugs in full bloom, veterans were getting extra chances. Rookies rebounded to 13 percent in 2003. There, they’ve remained. Rookies keep getting similar rates of opportunities, and that seems meaningful, because if teams couldn’t trust rookies to perform, they wouldn’t get into the lineup so much.

There’s one last thing I put together, using the Baseball America top-100 prospect lists that also go back 25 years. I looked at all the hitters on those lists who batted at least 100 times in the majors the season after getting ranked. I linked each player’s season wRC+, and here now, some three-year rolling averages. I’m showing both the mean and the median of the samples, although they predictably track closely with one another:

Last season, top-100 prospects averaged an 88 wRC+. But over the last three years, they’ve averaged a 95 wRC+, with a median of 94. These are right around the overall averages, and you see a bump in productivity after a bit of a lull in the vicinity of 2009. It’s possible that last year is just the start of something, and that rookies are going to be in a heap of trouble from this point forward. But last year doesn’t stand out as being particularly bad, as far as the modern era is concerned. Rookie productivity is down, but everyone’s productivity is down, so, relatively speaking, rookie productivity still seems fairly normal.

When you’re focusing on the negatives, it’s easy to overlook the things that went right. George Springer just had a big rookie year. So did Jose Abreu, and while Abreu wasn’t an ordinary rookie, he’d still never before played in the majors. Kevin Kiermaier was good, as were Danny Santana and Kennys Vargas. In Boston, while Bogaerts and Bradley were dreadful, Brock Holt was a pleasant surprise and Mookie Betts was outstanding. Some rookies have an easier time adjusting than others. This is how it’s always been.

One thing is absolutely true: Hitting in the major leagues has never been tougher. Pitchers have never thrown this hard, and there’s never been so much information, and there’s never been so much shifting and optimized defensive alignment. But hitting isn’t just harder for rookies and young players; hitting is harder for everybody. Young players have holes exploited, and the same goes for veterans. With a hotshot young offensive prospect, you should make sure to lower your expectations. But this is mostly just because you should lower your expectations for every hitter. Most of us just aren’t yet used to how pitcher-friendly the game has become.