Group members: Jarod Bacon, Jon Ince, Cooper Johnson, Noah Kastelman, Matthew LaMacchia, Andrew Riak, Grant Schmarak, Henry Sippel, Lorenzo Solon, Mariah Yelenick, Bailey Winston
Introduction (Adam Kaufman)
In today’s MLB, young talent is everything. The importance of free agency has diminished, and franchises are more focused than ever on acquiring promising young prospects and developing them into bonafide major league contributors. These prospects, while completely unproven at the major league level, represent enormous collective value to their franchises. According to a FanGraphs study, the strongest farm systems in the MLB had estimated surplus values upwards of $200 million. Individual top-tier prospects were estimated to be worth $50 million on their own.
A lot can go wrong, though, on the path from top prospect to MLB superstar. For every Alex Rodriguez or Mike Trout there’s just as many Brien Taylors or Mark Appels. MLB organizations focus much of their efforts on minor league player development, but it’s far from an exact science. Player makeup, college experience, and injury history are just a few characteristics that teams have little to no control over. On the other hand, teams do have the final say on when a given minor leaguer gets that coveted call to the big leagues.
For any decision as crucial as a major league promotion, there are many factors that impact the decision-making process. Minor league experience and success are two obvious ones, but major league injuries, 40-man roster restrictions, and even contract provisions can influence GMs to speed up or slow down a player’s timetable for promotion.
In our study, we wanted to take a deep dive into the timing of major league promotions, and investigate the true value of minor league experience to a top prospect’s development. The industry term “seasoning,” meaning the extra bit of experience a prospect needs before being deemed ready for the big leagues, is the crux of much of this research. Is there a developmental purpose to keeping a top prospect in the minors for an extra month or two? On the other hand, does calling up a prospect too early stunt their developmental growth?
To begin to answer these questions, our group began with a database of Baseball America top 100 prospects from 1990 to 2010. Since our questions revolve around the transition from minor league to major league, we needed a subset of players with a reasonable expectation to at least reach the majors.
From there, we decided upon baseline measurements of plate appearances and innings pitched to represent “experience” for batters and pitchers. With much help from Michael Lee’s Minor League Baseball Database, we were able to seamlessly collect this data for our sample of about 600 batters and 500 pitchers.
One big caveat: once a player made his major league debut, we stopped counting their minor league experience. These PAs and IPs were not only useless for our study, but actually detrimental. There’s two reasons why a player would return to the minor leagues after a major league debut:
- Injury rehab assignment
It should be clear enough why we chose not to count a rehab assignment in our study. Mike Trout, for example, recorded 15 plate appearances for the Angels’ Inland Empire 66ers A+ affiliate in 2017. Mike Trout is obviously no longer receiving minor league plate appearances for this purpose of his development.
For underperformance, though, we were at risk of ruining our dataset. If we counted minor league experience that was a result of major league underperformance, it would be clear in our analysis that the value of this experience is negative. Think about it. If all underperforming top prospects were forced to return to the minor leagues, then it would appear as though minor league experience causes major league underperformance. It’s a classic case of correlation not implying causality.
At last, with our completed dataset, we set out explore the relationship between minor experience and major league performance. As you’ll see below in our findings, some of the metrics used to define performance include WAR, wRC+, FIP-, and a few others.
If you’d like to check out our data, complete with in-depth minor and major league statistics for all 1100 Baseball America Prospects, you can access that here.
Non-Findings (Adam Kaufman)
There was a common belief held among the members of our group that the value of additional minor league experience was positive. The general line of thinking held that further preparation before exposure to the major leagues would only better prepare a top prospect for greater future successes.
As we quickly found, there appears to be no significant relationship between any measure of minor league experience (PAs/IPs) and major league performance. I won’t belabor this point, but I will display the two most prominent graphs that best illustrate this lack of a relationship.
While there are many reasons for a prospect to accumulate minor league playing time, the majority of minor league experience comes before a player’s professional debut. The mean number of total minor league plate appearances for a batter is 2,481, while 1,747 (~70%) of those occurred before any MLB playing time.
In general, players will be called up from the minor leagues only after showing signs of success, and left in the farm system to continue developing if otherwise. Based on this, one would assume that players with more overall minor league plate appearances will have less major league success. This is affirmed by the fact that Career WAR and total minor league plate appearances have a correlation of -0.487 (the negative shows that as a player records more minor league plate appearances, his career WAR will decrease). This discovery, while interesting, does include plate appearances recorded after a top prospects major league debut.
This shows that something as basic as how much time a player spent in the minors can predict a player’s career-long performance. This relationship is likely due to the fact that struggling players spend more time in the minor leagues after their initial debuts, but as stated before, most of a player’s time in the minors comes before their MLB debut.
Further, as one would assume, batters with college experience have significantly less minor league plate appearances than those without college experience do (p = 3.037 E-10). In line with this, there is a significant difference (p = 0.01) between Rookie Year WAR for college players and for those without college experience, with college players having a higher rookie year WAR on average.
However, while players with college experience perform better on average than others in their rookie year, this trend does not necessarily continue throughout the entirety of a career. When comparing the career WAR of the two groups, the p-value is a highly insignificant 0.8352.
Based on this, one could conclude that college experience will lead to early success, but over the course of a whole career, many other factors are at play.
Findings Pt. 2 (Adam Kaufman)
While it was a disappointment to find no significant relationship in the original area of analysis, our group had still managed to compile an impressive and valuable dataset that can be queried to answer other interesting questions.
For example, when examining the data using (admittedly) arbitrary percentile cutoffs, an interesting trend arises. Consider the graph below:
On the other hand, when performing the same analysis using WAR accumulated before exhausting rookie eligibility (rookie year WAR), something completely different stood out this time around. Below is the output.
Applications (Seth Coven)
Although there exists no statistically significant relationship between any measure of minor league experience and major league performance, we still believe that there are a few key takeaways from our research that can help teams best utilize their coveted minor league assets. While all decisions must be made on a case to case basis and are unavoidably conflated by extenuating factors such as health, roster restrictions, and contract provisions, we believe our findings provide sound empirical evidence to make the following general claims:
Prospects should be called up when deemed ready – The (non)finding that additional minor league experience had no correlation to major league success suggests that teams should not hesitate to call up minor leaguers to the majors when they are deemed ready. The general sentiment has been that calling up a prospect too early in their development may significantly hinder their growth and, in turn, be a detriment to their entire career success. Our findings suggest this is not necessarily the case. Taking it one step further, if a team is looking to “win now” and has a major hole that can be filled via promotion, there is no evidence to suggest that calling up a player to fill that hole will have any long-term consequences on that player’s career success. Fast-tracking a prospect through the minors may not, in fact, have any negative developmental repercussions (service time considerations aside).
One may suggest that of course there is no relation between minor league experience and major league success because teams specifically try to avoid making the mistake of calling up a prospect too early or too late. However, with a data set of 1,100 players, teams must have surely missed the mark with many of their promotions, providing us with a data set that reflects both good and poor promotions.
If you’re looking to “win now,” prioritize promotions of prospects who played in college – While there is no difference in career success between prospects with college experience and those without, college experience prospects have, on average, a higher Rookie Year War. Their additional experience playing in college seemingly provides an advantage when transitioning to the majors. Thus, a “win now” team looking to promote a player should, ceteris paribus, call up the player who played in college rather than the one who did not.
Promote the pitcher before you promote the batter – Say a team only has one roster spot open and they are looking to make a mid-season promotion in an attempt to secure their league’s final wild card spot. They have equally pressing needs at both first base and pitcher and have prospects at both those positions who have performed equally well in the minors. The data shows that this team should promote the pitcher rather than the first baseman, as the average rookie pitcher is worth 0.2 more wins above replacement than his hitter counterpart. While promoting the pitcher may not be the best decision for the team for future years, it will give them a slight advantage in the current season.
Conclusion/Future Research (Jarod Bacon)
The data did not provide any evidence that “seasoning” produced an effect on either rookie year or career WAR. One possible reason for this is that our data set included only the top 100 prospects of each year. Typically, top prospects are easily able to climb through the various levels of the minors without incident.
Additionally, about 43% of our sample consisted of players who played college ball before signing professional contracts. When college players are drafted, they are typically much more advanced and closer to making the majors than their high school counterparts.
Another factor to consider is how individual teams treat prospects. For example, some organizations accelerate their top prospects through the minors whether by choice or by organizational need. Conversely, others prefer to give them more time to develop or even hold prospects down longer to manipulate service time.
In the future, an updated project could look at all prospects and see if “seasoning” does indeed have an effect. Factors to consider are whether the player was drafted out of high school or college, what position they play, and what round they were drafted in. These can be used to see if the concept of “seasoning” impacts all players or just specific types of players.