The Final Step: Hitting in the Major Leagues

Few things are so exciting as a promotion. A promotion generally represents a lot of time, energy, and focus devoted to a role. While all promotions are special, there is a legitimate argument to be made that promotions in professional baseball are some of the most captivating.

Of course, professional baseball isn’t a typical career path or situated in a typical industry. However, even within the professional sports industry, MLB-affiliated professional baseball manages to separate itself due to the scale of its minor league system and the corresponding time that most players spend in that pipeline. The vast majority of players spend years working their way to the Major Leagues, and if they are talented (and surely fortunate) enough to ascend to MLB, it was likely considerably later relative to athletes in other sports. It also cannot go unmentioned that a promotion from AAA to MLB comes with one of the most dramatic pay increases (in both raw and percentage terms) really anywhere.

Given these circumstances, this post focuses on that promotion from AAA to MLB for position players. More specifically, what is typical for a player’s offensive production after making that final step, and who in recent memory handled their promotions the best, or worst?

The data used here originates from FanGraphs’ AAA and MLB leaderboards. In the case of MLB leaderboards, each player’s career numbers dating back to 2000 have been aggregated (not split by season); any player with 300+ MLB PAs from Opening Day 2000 – June 5th, 2022 is included. As for the AAA figures, FanGraphs records go back to 2006, so similar to the MLB data but with less historical data, all hitters with 300+ PAs in AAA between Opening Day 2006 and June 5th, 2022 are included.

300 plate appearances, for those wondering, is admittedly a pretty arbitrary threshold. It was chosen simply to capture players who got at least a “solid half season” at either level; theoretically enough playing time to allow for skill level to shine through in the context of small samples.

With both AAA and MLB hitting data on hand, career AAA wRC+ and career MLB wRC+ can be juxtaposed for qualifying players (300+ PAs at both levels within the timeframe). In all, 961 players satisfied both of these conditions.

Below is a histogram depicting the distribution of the difference between MLB and AAA wRC+ (wRC+ (MLB) – wRC+ (AAA)).

The values of MLB – AAA wRC+ are roughly normally distributed. The average drop-off in wRC+ among those players included here was 25; so hitters were on average 25% less productive relative to league average in MLB than they were in AAA.

It’s important to note that this sample likely isn’t particularly representative. There is some survival bias in this group as all the players included lasted in MLB long enough to accrue 300+ PAs; not all players hit well enough to last 300 PAs in the major leagues.

If anything, the distribution above highlights the difficulty in adjusting to MLB pitching; hitting in the upper minors is incredibly difficult, but making that final step is tougher still.

Some might note though that a handful of players actually appear to perform better (in terms of wRC+) in MLB than in AAA. Those players might be considered offensive “late bloomers”; below is a leaderboard of those players with the greatest MLB – AAA wRC+.

This list is filled with other familiar names, several of which are legitimate stars. Clearly, listing and sorting players who find a new gear only after reaching the majors makes for an interesting selection; one can find All Stars and MVP vote-getters up and down this list.

At this point in time, Will Smith leads the way. Having made just 368 plate appearances in AAA likely contributed to his pedestrian numbers there, but to this point in his MLB career, Smith has far outpaced his AAA production.

Of course, for every player that reached a new upper bound upon reaching the majors, there are many more who struggled to make the adjustment. The list below sorts players by lowest MLB – AAA wRC+ figures. These players might be thought of as emblematic of the “quadruple A” slight, reserved for players that couldn’t quite replicate their production from AAA in the major leagues.

Reaching the major leagues represents a finish line at the end of a path fraught with obstacles; every player on this leaderboard made it there and then lasted (or continues to play beyond) 300+ PAs, a considerable feat alone. Still, this group has a distinctly different complexion than the one prior. Players like Jabari Blash, Brandon Wood, and more recently, Lewis Brinson jump out as players who were never quite able to tap into their potential.

For someone like Gavin Lux though, it is simply far too early to say how their careers will continue to develop. Still, it is ominous that just three players of the 15 listed above managed 1000+ PAs in MLB after being so productive in AAA.

Lastly, the players below are those with the highest wRC+ in 300+ AAA PAs without having earned a PA in MLB.

Each of the players listed above hit 25+% greater than league average in AAA for his time and home ballpark.

Garrett Weber and Ernesto Mejia share the perhaps rough distinction as owning the highest wRC+ figures (136) among recent, inactive, players who never got a chance in MLB. Weber was a 35th round pick out of high school and later a 22nd round pick out of Fresno State; in 539 PAs at the AAA level from 2014-16 he slashed .322/.384/.512. Mejia, incredibly, played professional baseball from 2005 to 2021. While he slashed .279/.341/.513 in AAA he also played 8 seasons in Japan.

Fortunately, the majority (8 of 15) of this list is still active while looking for their final promotion. Players like top prospect Nick Pratto are all but a lock to earn MLB time, but one can never be certain. With any luck though, they will earn that final promotion sometime shortly after these words are written.